In this work, the support of two general galleries located in poor quality rock mass and subjected to the influence of high thickness coal layer exploitations is designed and optimized. The process is carried out in four phases:

A first preliminary support is defined employing different geomechanical classifications and applying the New Austrian Tunnelling Method (NATM) using bolts and shotcrete.

An instrumentation campaign is carried out with the goal of analysing the behaviour of the support. The study noticed the failure of the support due to the time of placement of the different elements.

A back-analysis using the Flac and Phases software has allowed the evaluation of the properties of the rock mass and the support, the study of the influence of the time of placement on the component elements (bolts and shotcrete), and the redefinition of that support.

Subsequently, a new support is designed and optimized through numerical modeling after the start of mining without experience in these sizes of sublevel caving that caused the failure of the previously designed support. The new support is formed by yieldable steel arches that are more suitable to withstand the stresses generated by nearby mining work.

Wet shotcrete technology is being gradually used in roadway support in frigid mining areas. Thus, problems such as low strength, fragility, and high repair rate have also emerged. This study focuses on low strength, cracking, and other problems in the wet shotcrete support of a mine. It introduced the fishbone diagram to investigate the effects of temperature, cement content, and water-cement ratio (W/C) on the strength of the shotcrete layer. The microscopic morphology of wet shotcrete based on scanning electron microscopy (SEM) is observed. Results demonstrated that temperature was the main influencing factor of wet shotcrete in frigid mining areas. When the curing temperature was lower than 10°C, the early strength of wet shotcrete dropped significantly. Temperatures above 15°C were favorable for later gain in strength. W/C was of a complementary relationship with strength development at different ages. Temperature was the essential factor that influenced the microscopic morphology of wet shotcrete. Furthermore, internal initial porosity and aggregate interface bonding strength had a direct effect on macro-mechanical properties of wet shotcrete.