Evaluation of the behavior of geotextile tubes used in environmental protection works
KEY WORDS: Geotextile tubes, environmental protection works, nonwoven geotextile, dewatering process.
The construction of structures to protect against floods, water diversions, breaking waves through conventional construction methods has led to an increase in the use of alternative methods, including the use of geotextile tubes. This method has quick implementation as well as reduced costs. Other uses with of geotextile tubes have been directed to the dewatering of fine-grained materials resulting from industrial processes or wastewater treatment with different concentrations. However, few studies have been carried out to understand the behavior of these structures in terms of the type of geotextile and filling material and technique. In this sense, the present work aimed to study the behavior of geotextile tubes used in environmental protection works. For this purpose, tests were defined using sandy and clayey soils as filling materials and non-woven geotextile in the manufacture of tubes. Thus, filling of single and stacked tubes conditions were carried out. The tests were instrumented in order to obtain variations in the height of the tubes, pore pressures in the filling material as well as the vertical stresses at the base of the tubes. Variations in the deformation of the geotextile were obtained during the test and samples of the soil particles passing through the geotextile were collected for the study of its retention capacity. In addition, vane tests were performed on the filling material to obtain its undrained strength. Results for tubes filled with sand allowed analyzing the rapid stabilization process of the dewatering process, as well as the stabilization of stresses and pore pressures at the base of the tube and served as a reference to calibrate the system. After this process, the clayey soils were used to fill single and stacked tubes. The results obtained showed that the initial dewatering process was characterized by pore pressure peaks and total stresses at the base of the tubes that stabilized over time. The greatest deformations in the geotextile were obtained at the end of the filling process with small variations during the test. The variation of undrained strength with depth in the stacked tubes and in two of the single tubes showed a decrease in strength with depth due to the impermeable condition of the foundation. All these results showed the importance of verifying the behaviour of the nonwoven geotextile both for isolated and stacked tubes, which can modify the geometry and influence the dewatering process, the strength of the filling material and the strains in the geotextile.