为安全高效的通过顶管法在垮落体中构建应急救援通道，探明顶进阻力的演变机制具有重要意义。通过结合物理相似模拟试验和数值模拟试验，对顶管过程中顶进阻力和垮落体颗粒宏观位移的演变特征进行了分析，并利用三维力链识别方法结合颗粒材料的力链屈服行为对顶进阻力的跌落特征进行了探讨。为进一步确定顶进阻力跌落特征的内在力学机理，选取颗粒堆积厚度、顶管半径、粒径及有效模量为正交因素，开展了针对顶管不同部位的顶管数值模拟试验。并在考虑力链屈服行为的基础上，结合顶进阻力跌落、接触失效、配位数突降、颗粒弹性势能释放和力链长度变化等顶进阻力及颗粒宏细观参数的变化特征进行了研究。结果表明：顶管过程中颗粒的宏观位移主要集中在顶管切口斜上方，且颗粒内存在较明显、连续的剪切滑移带，顶管阻力的跌落现象与局部范围内的颗粒失稳滑移和力链屈服行为相关联；顶进阻力跌落频率与管径和有效模量呈正相关关系，与颗粒厚度和粒径呈负相关关系，顶管切口试验的跌落频率明显大于顶管外壁试验，且顶进阻力的循环上升−跌落特征具有较高的相似性；力链长度及力链有效长度随着上覆颗粒厚度及粒径的增加而增加，扩大了力链影响范围，并进一步导致屈服接触分布范围、配位数变化幅度、力链压曲变形程度及弹性势能增加幅度的增加；垮落体在顶推作用下的力链屈服和解卡滑移，是颗粒内弹性势能释放、长力链分解的主要原因；顶管上方沿剪切面错动的颗粒在重力引导下的迅速失稳、跌落和堆积，是导致该部分颗粒弹性势能释放对顶管阻力整体影响较小的原因。

In order to establish an effective and secure emergency rescue channel within a collapsed structure using the pipe jacking method, understanding the evolution mechanism of jacking resistance is crucial. The evolution characteristics of the jacking resistance and the macroscopic displacement of the collapsed particles during pipe jacking process were analyzed by physical similarity simulation test and numerical simulation test, and the drop characteristics of the jacking resistance were discussed by using 3D force chain identification method and the force chain buckling behavior of the particle material. In order to further determine the intrinsic mechanical mechanism of the jacking resistance drop characteristics, the particle stacking thickness, pipe radius, particle size and effective modulus were selected as orthogonal factors, and the numerical simulation test at different parts of the pipe were carried out. On the basis of the force chain buckling behavior, the change characteristics of the jacking resistance and the macroscopic and microscopic parameters of the particles, such as jacking resistance drop, contact failure, sudden drop in coordination number, particle elastic potential energy release and force chain length change, were studied. The results show that: The macro-displacement of particles primarily occurs around the oblique top of the pipe jacking cut, where a distinct and continuous shear slip zone emerges within the particles. The decrease in jacking resistance is associated with the unstable slip of particles and the localized buckling behavior of force chains. The frequency of dropping jacking resistance positively correlates with pipe diameter and effective modulus, while negatively correlating with particle thickness and size. Notably, the dropping frequency observed in pipe jacking cut tests is higher than that in outer wall tests, and both exhibit cyclic rising-falling patterns with high similarity. As the thickness and size of the overlying particles increase, the length and effective length of force chains also increase. This extension expands the reach of force chains, leading to a broader distribution range of buckling contacts, changes in coordination numbers, degrees of buckling deformation within force chains, and in-creases in elastic potential energy. The buckling and slip of force chains within the collapsed body are key factors contributing to the release of elastic potential energy and the breaking down of extended force chains within particles. (5) The rapid instability, fall, and accumulation of particles along shear planes above the pipe jacking, guided by gravity is the reason why the release of elastic potential energy of these particles has little effect on the overall resistance of the pipe jacking.