RNPC-net: Automatic recognition and mapping of weathering degree and groundwater condition of tunnel faces

Accurate and rapid recognition of weathering degree (WD) and groundwater condition (GC) is essential for evaluating rock mass quality and conducting stability analyses in underground engineering. Conventional WD and GC recognition methods often rely on subjective evaluation by field experts, supplemented by field sampling and laboratory testing. These methods are frequently complex and time-consuming, making it challenging to meet the rapidly evolving demands of underground engineering. Therefore, this study proposes a rock non-geometric parameter classification network (RNPC-net) to rapidly achieve the recognition and mapping of WD and GC of tunnel faces. The hybrid feature extraction module (HFEM) in RNPC-net can fully extract, fuse, and utilize multi-scale features of images, enhancing the network's classification performance. Moreover, the designed adaptive weighting auxiliary classifier (AC) helps the network learn features more efficiently. Experimental results show that RNPC-net achieved classification accuracies of 0.8756 and 0.8710 for WD and GC, respectively, representing an improvement of approximately 2%-10% compared to other methods. Both quantitative and qualitative experiments confirm the effectiveness and superiority of RNPC-net. Furthermore, for WD and GC mapping, RNPC-net outperformed other methods by achieving the highest mean intersection over union (mIOU) across most tunnel faces. The mapping results closely align with measurements provided by field experts. The application of WD and GC mapping results to the rock mass rating (RMR) system achieved a transition from conventional qualitative to quantitative evaluation. This advancement enables more accurate and reliable rock mass quality evaluations, particularly under critical conditions of RMR.