Evaluation of geomechanical features and stability for the recommendations and rehabilitation of the Humberto Molina Hospital, Zaruma, El Oro, Ecuador

Abstract

Zaruma is a city with a mining tradition, located at 1,200 m above sea level, with natural conditions of high slopes. The existence of galleries under the city centre, originated by old and illegal mining works, has created conditions that impact the mining-society relationship of a technical-social nature, with concern about subsidence city's urban area. The areas of the Humberto Molina Hospital and its surroundings, such as the SJ Bosco School, have been affected by different geodynamic events, which has damaged infrastructure. The aim of this research is to assess the study area through geotechnical surveying, processing laboratory information, and direct field observation, using the approach of pre-design proposals containing technical solutions to ensure the safety of buildings. The methodology used consists of: (i) information processing and field surveys; (ii) drilling and pits work for sampling and determination of in-situ properties and laboratory work; (iii) interpretation of the results obtained, assessment of stability conditions through Spencer's method and consideration of the influence of underground work; (iv) analysis of susceptibility to slippage using the methodology of various authors; and (v) proposal of the pre-design of the technical security solutions. The study verified that the stability of the works are influenced, both by the physiographic factors and the incidence of nearby illegal underground work. Slope stability can be aggravated in extreme situations by seismic action, heavy rainfall, and migration of underground voids in the direction of the works. Susceptibility analysis determined that the terrain is in a stable condition, as the soil studied was categorized as medium to very good quality. Among the recommendations for the remediation of the Humberto Molina Hospital, it is suggested control of the drainage of rainwater and wastewater, use of vegetation, change of current fill, strengthening with concrete, and other basic considerations regarding building structures should be undertaken, associated with direct observation and geotechnical studies.