WU Feipeng1,2,ZHAO Zhiqiang1,YAN Bingfu2,DING Qianshen3,LIU Jing1,2,QI Ning1,2,LUO Mingliang1,2
JOURNAL OF VIBRATION AND SHOCK. 2024, 43(8): 193-201.
High-velocity and hydraulic kinetic energy fracturing can achieve hydraulic penetration impact with strong dynamic load. This technology mainly utilizes the water hammer effect, which has many unique advantages, such as high peak pressure, high loading rate, and repeated progressive expansion of cracks. The evolution mechanism of rock damage-fracturing process under the hydraulic penetration impact of charged fluid is the core issue in the optimization design of this technology. Therefore, a rock dynamic damage simulation experimental device was employed to conduct a series of rock dynamic failure experiments under strong hydraulic penetration impact. The influence law was analyzed based on loading rate, impact times, and combined repeated impact on rock failure morphology. The results indicate that, If a single hydraulic penetration impact is conducted on rocks, three different rock failure modes are presented in sequence as the loading rate increase. These are near wellbore crushing damage (8.5MPa/ms), forming macroscopic cracks due to the aggregation and concatenation of microcracks (13.4MPa/ms), fluid wedging brittle cracking (15.5MPa/ms). Under repeated impacts with low peak pressure and low loading rate, rock damage and failure exhibit three stages: near wellbore crushing damage (1-2 times), cracks initiation and propagation (3-5 times), and stress compression crushing (6-10 times). As the number of impacts increases, the damage around the hole intensifies, forming cracks of varying length.