To recommend the excavation procedures and design parameters for underground powerhouses, excavation procedures of fifty-one underground powerhouses in China were summarized and analyzed based on in situ stress conditions. Firstly, the complex stress environment in China was introduced and fifty-one underground powerhouses with their engineering scale, size, lithology, rock classification and in situ stress level were listed in detail. Subsequently, to evaluate the influence of in situ stress levels on excavation procedure design, the correlation between excavation procedures and in situ stress level in three main excavation zones were analyzed accordingly. Moreover, to provide the excavation design recommendations, the strength–stress ratio (SSR) was promoted to analyze and recommend the design parameters, and the blasting excavation design based on the stress transient unloading control was also supplemented. The results show that excavation procedures have different priorities under different in situ stress levels, and the design parameters show an obvious relationship with in situ stress levels. Moreover, the excavation procedure parameters are suggested to adjust accordingly under different SSR. The discussion of influencing factors and specification ensures its rationality and accuracy. It is believed that the summary and recommendations can provide a good reference for excavation procedure optimization of underground powerhouse under high in situ stress.

To analyze the effect of neighboring hole impacts on the inter-hole presplitting process, the dynamic cracking behavior under explosive load and ground stress is theoretically investigated by developing an inter-hole cracking model. Considering the variations in crack width, the influence mechanisms of stress waves from both in-hole and adjacent holes on the dynamic cracking process of presplitting blasting are examined through numerical simulations. Meanwhile, explosion tests under different detonation conditions were carried out to verify and further elucidate the dynamic effects of inter-hole presplitting blasting. The results indicate that the opening of presplitting holes can be restricted, reduced, or even closed during the cracking formation process due to the stress wave from adjacent holes when detonated simultaneously. Furthermore, there is a tendency for inter-hole cracks to be constrained in the large-angle direction, limiting crack propagation. And millisecond detonation timing can reduce the dynamic stress superposition effect between pre-cracked holes, thereby mitigating the damage to the surrounding rock. This finding is particularly applicable to presplitting blasting technology.