Understanding and predicting the propagation and disturbance of multiple fractures is the key to the successful implementation of hydraulic fracturing. In this study, the two-hole fracturing tests are carried out on granite samples by using soundless cracking demolition agent (SCDA). Combined with the extended finite element method (XFEM) simulation and the induced stress analysis, the interaction and stress interference during the propagation of two fractures are systematically investigated. The relative position of two holes determines whether attraction or repulsion effect occurs between adjacent fractures, the pattern of which can be classified into three modes: the fracture collinear, staggered propagation and parallel propagation. The fractures in collinear pattern are prone to coalescence, the staggered fractures are easy to attract each other and the parallel fractures tend to propagate independently, which ultimately lead to the formation of single, spiral and multiple main fractures, respectively. The stress near the fracture tip controls the possibility and direction of fracture propagation. The superposition of tensile stress is prone to promote fracture propagation, and the stress interference tends to make fractures deflection and mutual exclusion. The fracturing results are quantitatively evaluated by using fractal dimension and fracture surface characteristics. It is found that increasing perforation spacing makes the degree of internal rupture of the sample increase first and then decrease, and the fracturing scheme is optimal when the perforations are arranged perpendicular to the direction of maximum horizontal principal stress.

了解和预测多条裂缝的扩展和扰动是水力压裂成功实施的关键。本研究采用无声裂解剂（SCDA）对花岗岩样品进行双孔压裂试验。结合扩展有限元法（XFEM）模拟和诱导应力分析，系统研究了两条裂缝扩展过程中的相互作用和应力干扰。两孔的相对位置决定了相邻裂缝之间是否发生吸引或排斥作用，其模式可分为三种模式：裂缝共线、交错扩展和平行扩展。共线型骨折易发生交错裂缝易相互吸引，平行裂缝倾向于独立扩展，最终分别形成单条主裂缝、螺旋主裂缝和多条主裂缝。裂缝尖端附近的应力控制裂缝扩展的可能性和方向。拉应力叠加易促进裂缝扩展，应力干扰易使裂缝偏斜、互斥。利用分形维数对压裂效果进行定量评价和断面特征。研究发现，增大孔眼间距使样品内部破裂程度先增大后减小，当孔眼垂直于最大水平主应力方向布置时，压裂方案最优。