摘要
动态回弹模量测试仪(DEMT)是在动态变形模量Evd测试仪(PFWD)与车载式落锤弯沉仪(FWD)检测原理基础上研制而成。本研究旨在探究公路路基DEMT现场检测中动态回弹模量的真实值,比较分析PFWD动态变形模量与DEMT动态回弹模量定义上以及公式计算的差异,修正采用DEMT进行动态回弹模量检测时塑性变形对结果的影响。通过定制钢模制备不同掺灰量与不同压实度的土样试件,并使用高精度游标卡尺测量DEMT测试前后试件高度差。试验结果表明,掺灰条件下,压实度越低,试件可被压缩区间越大,受到冲击荷载时产生的塑性变形越大,压实度为90%,测试回弹模量值时初始塑性变形最大,为0.0532 mm,压实度为96%时,总变形中初始塑性变形最小,为0.0201 mm。由此可见,路基土试样进行动态回弹模量测试时塑性变形在总变形中的占比随压实度的增加而减小,且同一压实度试件随回弹模量测试次数的增加塑性变形占比逐渐减小。
The Resilience modulus Tester (DEMT) is developed based on the principles of the Dynamic De-formation Modulus Evd Tester (PFWD) and the Falling Weight Deflectometer (FWD). This study aims to explore the true values of the Resilience modulus (DEMT) in on-site testing of highway subgrade. A comparative analysis is conducted between the dynamic deformation modulus measured by PFWD and the Resilience modulus measured by DEMT. The differences in modulus definitions and formula calculations are analyzed, and the influence of plastic deformation on the results when using DEMT for Resilience modulus testing is corrected. Custom steel molds were used to prepare soil specimens with different fly ash contents and compaction degrees. The height difference of the specimens before and after DEMT testing was measured using a high-precision vernier caliper. The experimental results show that under fly ash conditions, the lower the compaction degree, the larger the compressible range of the specimen, and the greater the plastic deformation induced by the impact load. When the compaction degree is 90%, the initial plastic deformation is the largest, measuring 0.0532 mm. When the compaction degree is 96%, the initial plastic deformation is the smallest, measuring 0.0201 mm in the total deformation. Therefore, it can be observed that the proportion of plastic deformation in the total deformation during Resilience modulus testing of subgrade soil samples decreases with the increase of compaction degree. Moreover, for specimens with the same compaction degree, the proportion of plastic deformation decreases gradually with an increase in the number of rebound modulus tests.
出处
《交通技术》
2023年第5期438-448,共11页
Open Journal of Transportation Technologies
