Granular Cascading Motion Governs Fault Behavior

This dataset accompanies the study “Granular cascading motion governs fault behavior” and provides high-resolution four-dimensional (3D + time) X-ray computed tomography (CT) observations of granular fault gouge subjected to ring-shear deformation under controlled normal stresses. The experiments were conducted using a custom-built in-situ CT ring-shear apparatus, enabling direct visualization of particle-scale structural evolution during shear. Glass bead assemblies with different initial grain-size distributions were sheared under two representative normal stress conditions (0.6 MPa and 4.0 MPa), corresponding to intact-grain and crushing-mediated regimes, respectively. Time-resolved CT scans were acquired after consolidation and at successive shear stages (20, 40, and 60 minutes), capturing the spatiotemporal evolution of particle migration, segregation, fragmentation, and contact reorganization. The reconstructed volumes were segmented to identify individual particles and classify them into discrete size groups. The sample was further partitioned into vertical layers and concentric annular regions to quantify spatial heterogeneity along axial and radial directions. The dataset includes particle-scale statistics such as particle counts, grain-size distributions, coordination number, and porosity, as well as derived metrics describing cascading motion, densification, and structural reorganization. These data form the quantitative basis for identifying two distinct micromechanical regimes: a reversible granular cascade sustaining stick–slip instability under low stress, and a fragmentation-driven, fines-dominated regime in which cascade renewal is suppressed through kinematic isolation of coarse-grain triggers. This dataset is intended to support reproducibility of the published results and to serve as a benchmark for developing and validating discrete-element and continuum models of granular fault mechanics. It may also be useful for broader studies of shear-induced particle breakage, granular segregation, and frictional instability in geomaterials.本数据集配套于"Granular cascading motion governs fault behavior"（颗粒级联运动控制断层行为）研究，提供了受控正应力条件下受环剪变形作用的颗粒断层泥的高分辨率四维（三维+时间）X射线计算机断层扫描（CT）观测数据。 本实验采用定制化原位CT环剪装置开展，可直接观测剪切过程中颗粒尺度的结构演化过程。研究选用具有不同初始粒径分布的玻璃珠集合体，分别在0.6 MPa与4.0 MPa这两种典型正应力条件下进行剪切试验，分别对应完整颗粒主导与破碎介导的力学机制。 在固结完成后及剪切过程的20、40、60分钟三个连续阶段，采集时间分辨CT扫描数据，以捕捉颗粒迁移、分选、破碎及接触重组的时空演化过程。对重建后的三维体数据进行分割，以识别单个颗粒并将其划分为不同的粒径组别。此外，将试样进一步划分为垂直分层与同心环状区域，以量化轴向与径向的空间非均质性。 本数据集包含颗粒尺度的统计数据，如颗粒计数、粒径分布、配位数（coordination number）与孔隙率（porosity），同时涵盖用于描述级联运动、致密化及结构重组的衍生指标。上述数据为识别两种截然不同的微力学机制提供了量化基础：一是低应力下维持粘滑失稳的可逆颗粒级联机制，二是由破碎主导、以细颗粒为主的机制——该机制中粗颗粒触发体的运动学隔离会抑制级联过程的更新。 本数据集旨在支持已发表研究结果的可重复性，并可为颗粒断层力学的离散元（discrete-element）与连续介质模型的开发与验证提供基准参照。此外，该数据集还可用于岩土材料中剪切诱导颗粒破碎、颗粒分选及摩擦失稳等更广范围的相关研究。