Abstract
The aim of this paper is to study the transient flow caused by rapid filling and drawdown in levees constructed in order to protect urban areas exposed to flooding. In particular, the behavior of typical protection levees constructed in Villahermosa City in Tabasco Mexico affected by intense rainfalls at the end of 2007 is assessed. The analyses are performed by numerical modeling based on finite element method. The emphasis is on the study of time variation of flow velocities and hydraulic gradients in several points of interest within these structures. Results of parametric analyses varying magnitude and velocities of filling or drawdown are also given. Besides, the changing configuration of saturation and desaturation lines at different times of the transient flow is illustrated. Finally, general conclusions concerning these types of analyses are provided.
Highlights
The levees built near rivers, lakes and channel slopes are frequently subjected to sudden changes of water level, which modify flow conditions inside the soil mass
This paper focuses on studying the transient flow, the variation with time of flow velocities and hydraulic gradients which are generated within the levees protecting Villahermosa City against flooding as water levels increase and decrease because of the rain cycles and dams discharge in the region
The two last figures reveal that highest values of gradient and velocity (V,nax=1.2 x 10-2 mid) occur at the toe of downstream slope of levee. This hydraulic gradient is practically equal to the so-called critical hydraulic gradient, icc> which refers to effective stresses being zero, causing in the soil the phenomenon known as piping
Summary
The levees built near rivers, lakes and channel slopes are frequently subjected to sudden changes of water level (increments or decrements), which modify flow conditions inside the soil mass. Hydraulic gradients and seepage forces are developed that, in extreme conditions, can cause the total failure of the structure. These phenomena, known as rapid filling and rapid drawdown , are complex problems in which magnitude and velocity of filling or drawdown , hydraulic conductivity and porosity of materials constituting the levee, and geometry of slope and initial boundary conditions of flow are involved. This paper focuses on studying the transient flow, the variation with time of flow velocities and hydraulic gradients which are generated within the levees protecting Villahermosa City against flooding as water levels increase and decrease because of the rain cycles and dams discharge in the region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
