A hydrogeological approach in urban underground infrastructures
- Autores: Alejandro Serrano Juan
- Directores de la Tesis: Enrique Vázquez Suñé (dir. tes.), Xavier Sánchez Vila (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2016
- Idioma: español
- Tribunal Calificador de la Tesis: Sebastià Olivella Pastallé (presid.), Guido Luzi (secret.), José Fernández Torres (voc.)
- Materias:
- Enlaces
- Resumen
The competition for space in urban areas due to an exponential growth of population makes derground engineering plays a crucial role in the development of cities. Urban underground infrastructures deal with variables such as cost, duration, safety, and management; faces political, social, economic and environmental issues; and guarantees future sustainability, maintenance, and energy efficiency. To do so, all these concepts and variables must be kept in mind during the whole construction process: (I) project design, (II) project construction and (III) project exploitation. This thesis aims to demonstrate how the construction cycle deals with the various impacts produced by the interaction of underground constructions with groundwater at each stage of the process, with a view to providing improved processes. During the project design previous data is collected, new data is generated, created and processed, helping to understand the context and to design the infrastructure. There are very advanced tools to store and process hydrogeological data, but most of these tools are not common in infrastructure projects. Often most of the constructions only perform the minimum legal requirement to characterize the ground: a pumping test. Therefore, there is a need to provide the constructors with a set of methods and tools to allow them to increase the quality of their hydrogeological analysis, which will allow early detection problems associated with the groundwater.
The interaction of underground constructions with groundwater generates impacts. These impacts can usually be minimized by using mitigation measures. The most common impacts caused by underground constructions are the groundwater barrier effect and the groundwater pressure distribution and limitation under the bottom slab. In the literature there are many examples and designs to mitigate both groundwater barrier effect and groundwater pressure distribution impacts. However, there is no design that integrates both solutions. This thesis presents an innovative groundwater by-pass design that enables the groundwater to flow through the structure and provide a homogenous distribution of the water pressure under the bottom slab. The new integrated design was applied to the largest underground infrastructure of Barcelona: La Sagrera railway station. A hydrogeological model was implemented to test the original and the integrated designs in three different scenarios. This new solution mitigates the groundwater barrier effect and optimizes the bottom slab, considerably reducing the costs and increasing safety during the construction phase.
Monitoring is required when dewatering underground constructions in order to anticipate unexpected events and preserve nearby existing structures. The most accurate and spread monitoring method to measure displacements is levelling, a pointlike surveying technique that typically allows for tens of discrete in-situ sub-millimetric measurements per squared kilometer.
Another emerging technique for mapping soil deformation is the Interferometric Synthetic Aperture Radar (InSAR), which is based on SAR images acquired from orbiting satellites or by ground-based stations (GB-SAR). This remote sensing technique can provide better spatial point density than levelling, more extensive spatial coverage and cheaper acquisitions. Both satellite and ground-based SAR systems have been used and tested in a variety of analyses. However, nobody has applied this technology as a monitoring tool during construction works yet. This thesis contributes to data storing and data analysis software that implies new and significant method developments for increasing the quality of the hydrogeological analysis; it provides new approaches to address the groundwater corrective measures definition during the design stage, and it develops and applies new methods of nfrastructure monitoring using ground-based and satellite SAR sensors during the construction stage.
