Triaxial data, hydrostatic loading data, grain size image analysis data and processed representative elementary area (REA) for Bentheim, Castlegate and a synthetic sandstone sample

We examine the role of cement on compaction band formation by performing triaxial tests on three sandstones, Bentheim, Castlegate and a synthetic sandstone which possess very similar porosities (~26-29%) and grain sizes (~230-300 µm), but which are cemented differently, with syntaxial quartz overgrowths, clay, and amorphous quartz cement respectively. Each sample was taken to 5% axial strain at a starting effective stress equivalent to 85% of its hydrostatic yield (P*) value, which were identified from yield under hydrostatic loading. These data for the 3 samples are presented as matlab data files. Post-deformation, each of the 3 cores underwent backscatter SEM and subsequent image analysis to examine any localised variations in porosity and grain size. These data are presented as csv files. Discrete bands form in each of the 3 sandstones but are distributed differently across each sample. Our results suggest that cement type plays a significant role in the micromechanics of deformation within each of the sandstones, which in turn, determines where the compaction bands nucleate and develop. These results may provide a starting point to investigate the role of cement on compaction localisation further.

本研究通过三轴试验，针对3种砂岩开展系统测试以探究胶结作用对压实带形成的调控机制：试验所用砂岩包括本特汉姆砂岩（Bentheim）、卡斯尔盖特砂岩（Castlegate）以及人工合成砂岩。三者孔隙度（约26%~29%）与粒径（约230~300 µm）均极为相近，但胶结类型各异，分别为连生石英次生加大边、黏土胶结物以及无定形石英胶结物。
所有试样均在初始有效应力为其静水屈服（P*）值85%的加载条件下，被加载至轴向应变为5%；该静水屈服值通过静水加载下的屈服点确定。3组试样的试验数据以MATLAB数据文件形式提供。
变形完成后，对3块岩心依次开展背散射扫描电子显微镜（backscatter SEM）检测与图像分析，以表征孔隙度与粒径的局部变化特征，相关分析数据以CSV文件形式提供。
3种砂岩中均形成了离散压实带，但各试样内的带体分布模式存在显著差异。研究结果表明，胶结类型对各砂岩的变形微观力学机制具有显著影响，进而决定了压实带的成核与发育位置。本研究结果可为后续深入探究胶结作用对压实带局部化变形的影响提供基础参考。