Experimental analysis of soil cracking due to environmental conditions
- Autores: Josbel Andreina Cordero Arias
- Directores de la Tesis: Pere Prat Catalan (dir. tes.), Alberto Ledesma Villalba (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Hector Ulises Levatti (presid.), Antonio Lloret Morancho (secret.), Laura Asensio Sánchez (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Civil por la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
This thesis presents an experimental approach on the subject of cracking in soils due to changes in environmental conditions, where research is mainly directed to the soil-air interface and the effect of boundary conditions. At the theoretical level, hypotheses put forward by various authors on the cracking of soils in terms of origin and crack propagation are considered, which serve as a reference to describe the behavior obtained from the tests.
The objectives of the thesis belong to a line of research dedicated to studying the desiccation of soils and their implications in engineering works. The work consisted in the implementation of a one-year-long field test, subjected to natural environmental conditions, instrumented to monitor and record the main variables within the soil (temperature, volumetric water content, suction) and others very close to the ground-air interface area (wind speed and direction, temperature, relative humidity, solar radiation, rain intensity). For the laboratory experiments, significant improvements have been made in the existing environmental chamber to allow wetting of the specimens, and the automatic control of drying and wetting cycles. The cycles of humidity in the environmental chamber and the periods of rain and drought selected from the one-year-long field test measurements have been devised to study the behavior of the cracks in response to the variation of water content in the soil.
Several types of soil have been used for the development of the tests. One of the soils was a silty clay from the Campus Nord of the UPC in Barcelona, ¿¿already well characterized in works already published. Another soil, used in both laboratory and field experiments, is a silty clay from the Agròpolis agricultural campus in Viladecans. This clay is characterized in depth in this thesis. To study the cracking of soils as an effect of suction and contraction, mixtures of Jeddah sand (Saudi Arabia) with Gordon’s Kaolinite (United States) have been used.
The analysis of the results is based on concepts of classical soil mechanics and unsaturated soil mechanics, notions of agro-meteorology, application of techniques for image analysis and concepts previously developed in the research group. Some theoretical analysis has been carried out to explain the results obtained and to reach conclusions on the proposed objectives.
In general, the results of the laboratory experiments confirm some hypotheses and coincide with observations from previous published studies. The modified soil classification system RSCS has worked well as a tool to anticipate the transition of the capillarity phenomenon and the tendency to cracking by drying according to the input parameters required by that classification system. The combination of laboratory and field experiments has led to the conclusion that drying in the field is more efficient than in the environmental chamber, despite an extreme decrease of the relative humidity, given that there are natural variables that affect the boundary conditions and may have effects on the process of cracking in the ground.
