In order to study the load-bearing failure characteristics of a RPCCP under internal load, a field prototype test was designed, and a finite element model was established. An internal load was applied up to 2.0 MPa step by step and the force variation law of each part was obtained. During the production of the RPCCP, by wrapping prestressed steel bars around the concrete core with a cylinder, the core was subjected to an initial precompression stress. In the loading process, the protective cover cracked first, from where the concrete core gradually changed from the initial compression state to a tension state, finally cracking from the inner and outer diameter. The stresses of the cylinder and steel bars increased steadily with the internal load and did not yield. The finite element calculation results were in good agreement with the test results, and the influence characteristics of the tension control stress of the steel bar and the concrete strength on the failure of the RPCCP under internal load were discussed. The results showed that the internal load of the protective cover was independent of the tension control stress, but decreases with a decrease in concrete strength, while the load corresponding to the concrete core entering plasticity is related to the tension control stress and the concrete strength, and the relationships were basically linear.

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.

The K_R resistance curve for hydraulic crack propagation in a concrete beam was determined and discussed. A semi-analytical method was introduced to calculate the hydraulic crack propagation in concrete. A series of concrete beams with various hydraulic pressures and initial crack depths were tested, and the hydraulic crack propagation in these beams was calculated. The calculated P-CMOD curves were first verified, and then the calculated K_R resistance curve for hydraulic crack propagation was determined. Based on the test results and calculation results, the following conclusions can be drawn: The proposed analysis method can accurately predict the hydraulic crack propagation process in concrete. The K_R resistance to hydraulic crack propagation in concrete decreases with the increase in hydraulic pressure but is less influenced by the initial crack depth of the test beams. In addition, the concrete beams collapse immediately under hydraulic fracturing once the K_Iw curve reaches the K_R resistance curve. This indicates that the failure of concrete structures under hydraulic fracturing occurs immediately once the driving force of crack propagation, dominated by the hydraulic pressure in the crack, becomes significant.