Ensuring the high-quality construction of the ST Railway is a top priority for construction organizers and managers. In this paper, a stepwise approach combining bounding box (BB) technology and the Gilbert–Johnson–Keerthi (GJK) algorithm was proposed to determine the intersections between fractures. With the use of a stepwise approach, most of the nonintersecting fracture pairs were excluded, the computed speed and effectiveness were greatly improved compared with those in previous studies, and the length and direction vectors of the fracture intersections were obtained. A 3D discrete fracture network (DFN) model was generated and validated according to fracture data acquired from the right bank slope of the Nujiang Grand Bridge (NGB) of the ST Railway by unmanned aerial vehicle (UAV) photogrammetry technique. Based on the DFN model, the stepwise approach was implemented for intersection analysis and connectivity analysis. Connectivity parameters, including the number of intersections per unit volume and the intersection length per unit volume, were calculated as 1.279 m^-3 and 2.296 m^-2, respectively. The intersection analysis suggested that the mean length of the intersections was 1.796 m, and fracture sets 2 and 3 constituted the main flow pathways and played a predominantly combined cutting role for the rock masses in the study area. In addition, the investigation of the direction vector of the intersections indicated that the combined cutting action of fracture sets 2 and 3 easily formed wedge-shaped failure surfaces, and the lateral expansion produced by bedrock fracture groundwater was also unfavourable to the stability of the slope.

确保ST铁路高质量施工是施工组织者和管理者的头等大事。在本文中，提出了一种结合边界框（BB）技术和Gilbert-Johnson-Keerthi（GJK）算法的逐步方法来确定裂缝之间的交点。采用逐步法，排除了绝大部分不相交的裂缝对，计算速度和有效性较以往研究有了很大提高，得到了裂缝相交的长度和方向向量。利用无人驾驶飞行器 (UAV) 摄影测量技术，根据 ST 铁路怒江特大桥 (NGB) 右岸边坡采集的裂缝数据，生成并验证了三维离散裂缝网络 (DFN) 模型。基于DFN模型，采用逐步方法进行交叉分析和连通性分析。连通性参数，包括单位体积的交叉点数和单位体积的交叉点长度，计算为1.279 m^-3和 2.296 m ^-2。交会分析表明，交会的平均长度为1.796 m，裂缝组2和裂缝组3构成了主要的流动通道，对研究区岩体起着主要的联合切割作用。此外，交会方向矢量研究表明，裂缝组2、3的联合切割作用易形成楔形破坏面，基岩裂缝地下水产生的侧向膨胀也不利于边坡的稳定。 .