Search

One of the most common solutions to access the underground is through the construction of circular shafts. At a preliminary design stage, analytical expressions are often used to estimate the horizontal earth pressure acting on the lining. However, most of these solutions are based on active state conditions and do not consider the restrictions imposed on the shaft lateral displacements by the rigidity of its lining or by the construction method employed. To overcome this limitation, a new methodology to account for the shaft lateral displacements in the determination of the horizontal earth pressure acting on circular shafts is developed and validated against the results of relevant physical scale models. The obtained results show good agreement with the measured data, adequately reproducing the reduction in the horizontal earth pressure from its initial value to an active state condition with an increase in the shaft lateral displacement. Following this approach, more realistic predictions of the earth pressure acting on the lining of circular shafts can be performed.

Reducing carbon dioxide (CO2) emissions is a global priority. The concrete industry has a major role in this reduction since it accounts for about 8% of global CO2 emissions. Despite significant improvements in the sustainability of the production of concrete, one of the best solutions is still to improve the design and construction methods, such that the required quantities of concrete are reduced. Using, as a reference, a real case study, this study compares alternative shaft construction methodologies from engineering and sustainability points of view, highlighting the advantages and drawbacks of each solution. To achieve this purpose, a back analysis is performed to ensure that the numerical model is accurately calibrated and the shaft construction methods can be adequately assessed. The results show that, while the considered methods are applicable and satisfy engineering requirements, the characteristics of the lining of the shaft could have been optimized, resulting in a reduction in CO2 emissions by at least 50% without compromising the safety of the construction.