ABSTRACT
The focus of this Thesis is reinforced soil structures with polymeric (or geosynthetic) reinforcement elements. These materials are known for their rate-dependent behaviour, that is, time, load, temperature, and, to some extent, humidity, will affect their mechanical response. Depending on the geographic location of the structure, in-air and in-soil conditions can vary widely in temperature values and moisture content. Moreover, current climate change conditions, which are only expected to worsen with time, have shown drastic changes in local and global climate patterns, highlighting the need to better understand the response of reinforced soil structures to changing conditions. Coupled (thermo-hydraulic) numerical simulations were carried out to better understand how atmospheric climate influences in-soil conditions of a reinforced soil mass, namely, temperature, moisture content, and degree of saturation. Results allow for a better understanding of in-soil response to changing atmospheric conditions, as well as a valuable precursor for future coupled modelling attempts.
Pullout tests were carried out using polyester strap reinforcements to study the effect of in-soil temperature on the soil-reinforcement response (i.e., pullout strength and friction interaction factors). Likewise, different geometries, vertical pressures, and installation techniques were tested to evaluate the overall pullout response of strap reinforcements, possible damages due to displacements and their consequences in the long-term, as well as reinforcement stiffness and extensibility. Results are useful in practical- and research-related fields as they allow for determining the soil-reinforcement interaction factor in a wide range of conditions and provide a better understanding of the temperature dependencies in the mechanical response of polyester.
Polymeric materials will suffer from long-term deformations when subjected to constant load conditions. This phenomenon, also known as creep, will depend on the load level as well as temperature conditions. Analytical and numerical models usually rely on the selection of a single stiffness value to determine the response of polymeric materials. The selection of this value is not trivial, as it will depend on time, load, and temperature. With the aim of providing a numerical tool to simulate the long-term response of reinforced soil structure, a coupled viscoplastic constitutive model with temperature, load, and relative humidity dependencies was developed. Model parameters were calibrated using a wide dataset of laboratory measured creep master curves and later implemented in a finite element software.
Polymeric materials cover a wide range of solutions in the fields of civil, mining, and geotechnical engineering. A key advantage of these materials is their reduced environmental impact, attributed to reductions in the use of granular material and subsequent transportation efforts. This Thesis goes a step beyond environmental impacts and into sustainability assessments of reinforced soil walls. For this, different facing elements and backfill material alternatives were analysed. Assessments include environmental, social/functional, and economic requirements. A probabilistic approach was used for the environmental and economic requirements. Results use idealized scenarios to evidence the advantages and/or disadvantages of different alternatives for reinforced soil walls with rigid facings. Finally, the procedure and results serve as an example and/or starting point for future sustainability assessments, which are expected to be determining in future infrastructure projects.
PhD Advisors
- Prof. Ivan Puig Damians
- Prof. Sebastià Olivella Pastalle
PHD CANDIDATE
Mr. Aníbal Andrés Moncada Ramírez is a researcher at CIMNE’s Geomechanics and Hydrogeology research cluster.