Hydraulic Considerations and Construction Procedures at the Sinkhole Site of Cuernavaca’s Expressway

Mexican Institute of Water Technology, Mexico

Abstract: On July 12, 2017, at 5:50 am, a sinkhole collapsed in the so-called “Paso Express Tlahuica”, an expressway in the city of Cuernavaca, Morelos. The sinkhole formed at the junction of the Mexico-Acapulco Highway and the “Santo Cristo” creek, months after such freeway was extended from four to ten lanes. Because of this sinkhole, two people died, and traffic was disrupted for several weeks. This article gives a detailed description of the hydraulic considerations made in the design of the stream crossing of the highway extension, as well as the construction procedures that led to the formation of the sinkhole. A description is made of the sinkhole and its enlargement as the water current, coming from the Santo Cristo creek and originally running through a concrete pipe that became fractured, began to flow through the foundation of the expressway extension embankment. Mention is made of the phenomenon of piping that caused the sinkhole in the new embankment. The embankment consisted of granular material poorly compacted during its construction. The article includes conclusions and recommendations to avoid problems related to the internal erosion of soils susceptible to this phenomenon, especially in such important works as federal freeways that are part of the national infrastructure. Standing out among these conclusions is the fact that the filling material and the compaction carried out on the embankment for the expressway expansion of four to ten lanes were not appropriate for the type and magnitude of the work.