The long-term stress analysis of engineering projects can be significantly expedited if we can determine an appropriate rheological model and its corresponding parameters. In the present contribution, we show that an accurate and real-time estimation of rheological parameters is possible by employing deep learning and metaheuristic algorithms. A real-time back-analysis technique was proposed using a deep long short-term memory neural network (DeepLSTM) as a substitute for numerical modelling and firefly algorithm (FA) to search for the optimum parameter. The performance of the proposed technique, the DeepLSTM-FA, was verified using a tunnel response with the FLAC 2D finite difference program. Furthermore, the application of the DeepLSTM-FA to an engineering instance, namely, the Adriatic Motorway near Draga Valley, was discussed in detail, revealing that the DeepLSTM-FA can provide practitioners with an accurate and real-time estimation of rheological parameters, thereby allowing for timely stress and stability analyses. We found that an accurate estimation of rheological parameters can be made using the first few points of displacement data instead of the whole displacement profile. This technique extends recent efforts to determine rheological parameters in real time and significantly accelerates the application of stress and stability analyses in the future.