Download Soil fracturing induced by Mexico City subsidence / Fracturation du

Soil fracturing induced by Mexico City subsidence / Fracturation du sol causée par les
tassements de la ville de Mexico
Gabriel Auvinet
Instituto de Ingeniería, UNAM, Mexico City, Mexico, [email protected]
Edgar Méndez-Sánchez
Instituto de Ingeniería, UNAM, Mexico City, Mexico, [email protected]
Moisés Juárez-Camarena
Instituto de Ingeniería, UNAM, Mexico City, Mexico, [email protected]
Thème(s) / Theme(s): Theme 3. Natural hazards
ABSTRACT / RÉSUMÉ
During the last decades, an increasing number of soil fractures have been detected in Mexico City valley. Such
craks are a matter of growing concern for the population and authorities since they have caused a series of
accidents and serious damage to constructions and public services. It is now acknowledged that the soil fracturing
problem is an important risk factor and that the best scientific tools and techniques should be mobilized to define
prevention and mitigating measures. Field observations and surveys of actual cracks performed by different
groups, including Laboratorio de Geoinformática, Instituto de Ingeniería UNAM, for Mexico City basin subsoil have
provided valuable physical evidences that allow a classification of the different types of cracks for this region.
Soil fracturing can occur as a consequence of any condition leading to large tensile stresses or extension strains in
the soil. Accordingly, cracks in the soil have different origin, including contraction of compressible clays by drying,
stresses induced by the weight of constructions, hydraulic fracturing of soft soils, seismic movements, etc.
However, the largest and more destructive fractures are generally a direct consequence of land subsidence
associated, in the case of Mexico City, to pumping of water in deep aquifers.
Today, the subsidence phenomenon, at eighty years from Roberto Gayol’s discovery, and more than sixty years
from its scientific explanation by Nabor Carrillo (1947), persists with cumulative effects through time which cause
differential settlements in the colonial and modern structures of Mexico City. Metropolitan installations as important
as the subway system, the Gran Canal, and the water system network are also severely affected. From the historic
information which was gathered with the support of different institutions, the subsidence history of Mexico City
could be reconstructed. A Geographic Information System was elaborated. From the elevation contours map, a
model of cumulative configuration through time of the surface relief of the bottom of the former lakes was built
(Méndez et al., 2010)
In this paper an updated spatial distribution of subsidence in the former lacustrine area of Mexico valley is
presented together with a map of associated fracturing. The prevention and mitigation measures being considered
and implemented to control this problem are also discussed.
REFERENCES
1. Edgar Méndez, Gabriel Auvinet, Moises Juárez, Miguel Flores, Diego Pérez & Ulises Matus (2010). Recent
information on Mexico City subsidence. Proceedings of Symposium Land Subsidence Associated Hazards
and the Role of Natural Resources Development, International Association of Hydrological Sciences IAHS
Publication 339, Querétaro, México.