Effectiveness of Deep Drainage Wells as a Slope Stabilization Measure: The Reactivation of the Diezma Landslide (Southern Spain)

Abstract

The effectiveness of the stabilization measures, particularly deep drainage wells, have been analysed in a complex landslide affecting a major motorway in Southern Spain. A complete failure analysis of this instability, named as the Diezma landslide, has been performed considering different steps: (1) The slope before and after the A-92 motorway construction; (2) The slope during the 2001 Diezma landslide; (3) The slope after the stabilisation measures; (4) The slope at the 2010 reactivation; (5) Possible future reactivation. The good performance of the drainage wells was verified successfully by means of electrical resistivity tomography cross-sections. The future stability of the Diezma landslide depends on the correct performance of the drainage systems after periods of heavy rain. In addition, the reactivation of the Diezma landslide is expected in the case that a low magnitude earthquake (Mw 4.0–5.0), relatively common in the study area, occurs close to the landslide location.