In-stream mining: supporting and undermining critical infrastructure =
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Date
2019
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción.
Abstract
Sand and gravel mining are crucial to support massive construction and thus, countries
development and economies. Best quality sand and gravel for construction are obtained
from the riverbeds through in-stream mining. However, important geomorphological,
hydrological, and ecological impacts of in-stream mining have been recognized.
Importantly, river incision caused by sand and gravel extraction overlaps with local scour at
bridge piers increasing bridges’ failure risk. Are all in-stream mining activities dangerous
for bridges? Is there a threshold mining volume that causes damage to bridges? How
important to scour are the number of extractions around a bridge and what is the effect of
the distance between a bridge and the mining pits? Are there management options to reduce
bridge failures due to in-stream mining? In this thesis, we answer these questions based on
results from a statistical analysis of the relationships between 379 in-stream mining
activities and 30 bridges located over 10 major Chilean rivers, 21 bridges along 950 km of
the Panamerican route between the cities of Santiago and Osorno. Obtained results show
that: (1) scour at bridges is explained (>80%) by the extraction volume of the largest
mining activity, (2) a large (>300.000 m3
/year) and single extraction is more damaging than
several smaller extractions with the same total extraction volume, and (3) the distance
between extraction and bridge affects bridge scour only in cases of large extraction
volumes. Policies need to be urgently improved to allow river morphology to recover from
in-stream mining and to avoid bridge damage. Regulation of the mining volume and rate,
minimum distance between a bridge and a mining pit, and promotion of smaller activities
distributed along the river, instead of big, localized mining is recommended.
Description
Tesis para optar al grado de Magíster en Ciencias de la Ingeniería con mención en Ingeniería Civil.
Keywords
Socavación en Puentes, Agregados (Materiales de Construcción), Minería Hidráulica, INDUSTRIA, INNOVACIÓN E INFRAESTRUCTURA, CIUDADES Y COMUNIDADES SOSTENIBLES