Study on dynamic load stress transfer hindered by air/water medium fractures

Abstract Hydraulic fracturing technology leads to the development of lots of fractures in the surrounding rock reservoir, forming a three-dimensional fracture network, which plays a role in hindering the transfer of high stress. Under temporal-spatial influence, however, the fracture networks of different media will appear, mainly including water medium fractures and air medium fractures. Clarifying the influence of different medium fractures on the stress transfer is quite important for the layout of the three-dimensional fracture network. In this study, the effects of air and water medium fractures on stress transfer were explored through fracture mechanics theory, and Split Hopkinson Pressure Bar (SHPB) test. Under the joint action of fractures and stresses, the rock mass will form an undamaged zone, a damaged zone around the fracture, a damaged zone under the primary action of stress wave, and the damaged zone under repeated action of reflected stress wave, a model of dynamic load stress transfer hindered by fractures is established, through SHPB test study on dynamic load stress transfer hindered by air/water medium fracture, composite sized fractures, and different impact rates, the correctness of the model is verified by comparing the theoretical datas and experimental datas. The results show that air medium fractures can hinder the transfer of stress wave and form a large number of reflected waves to damage the rock mass.The water medium fracture can gather energy, act on the surrounding broken rock mass, form confining pressure, and increase the strength of rock mass, making it difficult to destroy the rock mass under stress action. With the increase of impact energy, the energy absorbed by fractures in water medium is limited, and a large number of stress waves damage rock mass.