Investigation of unbound granular material behavior using precision unbound material analyzer and repeated load triaxial test
Investigation of unbound granular material behavior using precision unbound material analyzer and repeated load triaxial test
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DOI：
10.1016/j.trgeo.2018.10.006
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发表时间：
2019-03-01
影响因子：
5.3
通讯作者：
Li, Rui
中科院分区：
文献类型：
--
作者：
Li, Ning;Wang, Hao;Li, Rui
本研究旨在利用高精度松散材料分析仪及重复荷载三轴试验，探讨松散颗粒材料的力学特性。本研究采用单一粒径与混合粒径集料及两种级配材料进行多阶段加载试验。考虑颗粒尺寸对UGM性能的影响，分析了6种颗粒材料的围压、回弹模量和永久应变。试验结果表明，随着大粒径颗粒的增多和结构的致密化，围压逐渐减小。当轴向载荷应力大于40 kPa时，弹性模量对颗粒尺寸敏感。采用变围压模型计算的高密度材料的回弹模量大于采用恒围压模型计算的高密度材料的回弹模量。结果表明，在分析围压和回弹模量时，应考虑轴向荷载、材料类型和最大粒径等因素。在不考虑围压的情况下，CCP模型对高密度材料的回弹模量可能低估，而对低密度材料的回弹模量可能高估。在10 kPa至20 kPa围压范围内，使用RLTT测量的弹性模量和永久应变与使用ARMA测量的弹性模量和永久应变相似。CCP模型和RLTT预测的永久应变与实验测量相比，误差大于VCP模型和WARMA测试的预测。试验中采用的动态围压能有效地模拟UGM在路面中的实际加载情况。RLTT试验和CRAMA试验对UGM的力学性能的表征结果基本一致，但CRAMA试验在模拟围压和测定回弹模量方面能提供更合理的结果。
This study aims to investigate the mechanical behavior of unbound granular materials (UGM) the using precision unbound material analyzer (PUMA) and repeated load triaxial test (RLTT). Both single-size and mixed-size aggregate and two graded materials were used for multi-stage loading tests in this study. The confining stress, resilient modulus, and permanent strains of six granular materials were analyzed considering the effect of particle size on the performance of UGM. The results of PUMA tests showed that the confining stress became smaller with more large-size particles and denser structure. Resilient modulus was found to be sensitive to particle size when the axial load stress was greater than 40 kPa. The resilient modulus of high-density materials calculated from the variable confining pressure (VCP) model was greater than that from the constant confining pressure (CCP) model. The results suggested that axial load, material type, and the largest particle size needed to be considered for analysis of confining stress and resilient modulus. Without considering confining stress, resilient modulus might be underestimated for high-density materials but overestimated for low-density materials using the CCP model. The resilient modulus and permanent strains measured using the PUMA were similar to those measured using the RLTT in the range of 10 kPa to 20 kPa confining stress. The predicted permanent strains from the CCP model and RLTT had greater error than the predictions from the VCP model and PUMA tests compared to experimental measurements. The dynamic confining stress in PUMA tests was found effectively to simulate the actual loading condition of UGM in a pavement. Although RLTT and PUMA tests present consistent results for characterizing the behavior of UGM, the PUMA can provide more reasonable results for simulating confining stress and measuring resilient modulus.