Researches Concerning the Configuration of Geotextiles in the Execution of Regulatory Works in the Riverbeds

The paper deals with the behaviour at hydrodynamic action of the geotextiles used in carrying out the regularization and shore defence works located in riverbed. The geotextiles have lately presented applications for the execution of bottom thresholds, of the management dams in riverbed. Also, geotextiles have become an important component in the structure of river defence works on riverbeds. The research was carried out on the lower course of the Moldova River in the area of Pildesti, Neamţ County. The dynamic action of the floods, through the liquid and solid flows, influences the stability and the resistance over time of the constructions made from geotextiles. The researchers analysed the behaviour of the geo-bags made of polyester bags filled with local materials (sand and gravel stabilized with cement), used in the structure of the bottom thresholds, steering dams and in the shore defence works. The research results indicate a differentiated behaviour of the geo-bags depending on the location (in the water, or on the shore) and the mode of action of the water (dynamic or static). The action of the water, through the liquid and solid flow, degraded the structure of the geo-bags by breaking and emptying the filling material. The geo-bags showed a reduced resistance to the action of the alluvial material, especially when the dosage of cement indicated by the design was not achieved. The research highlighted the good behaviour of the geo-bags in the erosion phenomenon of the riverbed, when they were mulched on the erosion zones and ensured the continuity of the constructions in the riverbed (bottom thresholds and shore defences)