The beneficial role of stratigraphy on slope stabilization by drainage trenches: results of FEM numerical analyses.

<p>Slope stabilization through drainage trenches is a classic approach in geotechnical engineering. Considering the low hydraulic conductivity of the soils in which this measure is usually adopted, a major constraint to the use of trenches is the time required to obtain a significant pore pressure decrease, here called &ldquo;time lag&rdquo;. In fact, especially when the slope safety factor is small, the use of drainage trenches may be a chancy approach due to the probability that slope deformations will damage the system well before it will become fully operative.</p> <p>However, this paper shows that the presence of persistent pervious natural soil layers in the slope can provide a significant benefit by increasing drainage efficiency and reducing time lag. As a matter of fact, any pervious layer that is intercepted by trenches may operate as part of the global hydraulic system, reducing the drainage paths.</p> <p>A simplified approach to design a drainage system accounting for the presence of a persistent pervious layer is proposed. This approach, which can exploit solutions available in literature for parallel drainage trenches, has been validated by numerical analyses.</p>