微震／声发射（acoustic emission, AE）技术可以有效监测干热岩储层水力压裂过程中裂缝扩展行为，为研究天然裂缝对裂缝扩展的影响，开展青海共和盆地花岗岩真三轴水力压裂室内物理模拟实验，基于含天然裂缝与完整花岗岩样品水力压裂过程中的声发射监测数据，结合注入压力曲线、裂缝形态、扫描电镜（scanning electron microscope, SEM）图像以及数值模拟结果，分析含天然裂缝与完整花岗岩的裂缝演化及声发射参数特征。结果表明：天然裂缝的存在显著降低了岩石的破裂压力，含天然裂缝花岗岩破裂压力（17.3 MPa）比完整花岗岩（20.8 MPa）降低了约17%。注入水压主要作用于天然裂缝面，促使其进一步扩展。但在应力分布的影响下，仍可能在最大主应力方向附近产生新的分支裂缝。当水平主应力差较大时，裂缝沿最大水平主应力方向扩展，更容易形成单一的优势通道。低水平应力差条件下，裂缝扩展受到更均匀的应力分布影响，裂缝网络向四周辐射，整体损伤面积增加，容易形成复杂的裂缝网络。声发射AF/RA值反映出花岗岩水力压裂裂缝以拉伸裂缝为主，声发射响应特征和泵送压力曲线变化具有一致性，表现出明显的阶段性演化特征。研究结果可为现场微震监测水力压裂过程提供参考。

Microseismic and acoustic emission (AE) technologies can effectively monitor fracture propagation during hydraulic fracturing in enhanced geothermal reservoirs. To investigate the influence of natural fractures on fracture propagation, the true triaxial hydraulic fracturing physical simulation experiments using granite samples from the Gonghe Basin in Qinghai Province were conducted. Based on AE monitoring data collected during the hydraulic fracturing processes of granite samples with natural fractures and intact granite, combined with injection pressure curves, fracture morphology, scanning electron microscope (SEM) images, and numerical simulation results, the evolution of fractures and AE parameter characteristics in the two types of samples were analyzed. The results indicate that the presence of natural fractures significantly reduces the fracture pressure of the rock. The fracture pressure of granite with natural fractures (17.3 MPa) is approximately 17% lower than that of intact granite (20.8 MPa). The injected water pressure primarily acts along the surfaces of natural fractures, promoting their further propagation. However, under the influence of stress distribution, new branch fractures may still form, mainly concentrate near the direction of the maximum principal stress. Under high horizontal principal stress differences, fractures propagate along the direction of the maximum horizontal principal stress, making it easier to form a single dominant flow channel. Under low horizontal stress differences, fracture propagation is influenced by a more uniform stress distribution, resulting in a radial fracture network, increased overall damage area, and the formation of complex fracture systems. The acoustic emission AF/RA value reflects that hydraulic fractures in granite are predominantly tensile. Acoustic emission response characteristics and changes in the pumping pressure curve exhibit a high degree of consistency, revealing distinct staged evolutionary characteristics. These findings can serve as a reference for field microseismic monitoring during hydraulic fracturing operations.