In this study

the rock fracture propagation is simulated based on the ordinary state-based peridynamics

and a numerical model of rock hydraulic fracturing is proposed by means of real-time tracking of newly generated fracture and applying pressure to simulating the interaction between fracturing fluid and fracture surface. According to the digital image processing technology

the Zhang-Suen thinning algorithm is applied to extracting the skeleton of hydraulic fracture network

and a quantitative method of hydraulic fracture network is presented by using the statistical method to calculate the morphological parameters. Finally

the process of hydraulic fracture propagation and the evolution of fracture network morphological parameters are studied considering the effects of loading rate

in situ stress condition and elastic modulus. The results show that when the loading rate is small

the main fracture expands towards the direction of the larger in situ stress

and the fracture branch is not obvious. Increasing the loading rate can increase the average width and density of fractures

promote the opening degree and number of fractures

enhance the complexity of fracture network

and improve its permeability. When the horizontal and vertical in situ stresses are the same

the major fractures intersect. With the increase of vertical in situ stress

the horizontal fractures are restrained

the major fracture propagates along the vertical direction

and the total length and density of fractures increase. The increase of elastic modulus of rock mass can reduce the propagation of fracture branches and simplify the fracture network.