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首页> 外文期刊>Transportation Research Record >Subgrade Characterization Employing the Falling Weight Deflectometer
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Subgrade Characterization Employing the Falling Weight Deflectometer

机译：利用落锤挠度计进行路基表征

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Subgrade soil characterization expressed in terms of resilient modulus (M_r) has become crucial for pavement design. For new pavement design, M_r values are generally obtained by conducting repeated load triaxial tests, employing TP46/P46 protocol. Because of the complexities encountered with the test, in situ tests would be desirable if reliable correlations could be established. This study investigates the viability of using the falling weight deflectometer (FWD) for direct testing of subgrades with the objective of deriving resilient moduli by means of a correlation between FWD moduli and TP46 M_r values. Ten as-built subgrade sections, reflecting typical subgrade soil materials in Mississippi, were selected and tested with the FWD. Undisturbed samples were extracted by using a Shelby tube and tested in a repeated-load triaxial machine for M_r, employing the TP46 protocol. In addition, other routine laboratory tests were conducted to classify the soils. In the suggested approach making use of seven FWD sensor deflections, elastic moduli, E_1 to E_7, are calculated through forward calculation equations (assuming an elastic half-space). The first sensor modulus, E_1, and an average offset sensor modulus, E_(3-5) (i.e., the average of E_3, E_4, and E_5), are regressed against M_r, advancing two models for M_r prediction. By employing E_1 and E_(3-5), two distinct resilient moduli are derived with the lesser of the two serving as the "design resilient modulus." A feature of the approach is that the entry into the process of both the center sensor modulus and the offset sensor modulus ensures proper subgrade characterization, even when significant nonhomogeneity in a subgrade profile is being encountered.
机译：以弹性模量（M_r）表示的路基土壤特性对于路面设计至关重要。对于新的路面设计，M_r值通常是通过使用TP46 / P46协议进行重复载荷三轴测试获得的。由于测试遇到的复杂性，如果可以建立可靠的相关性，则希望进行原位测试。这项研究调查了使用落锤挠度计（FWD）直接测试路基的可行性，目的是通过FWD模量与TP46 M_r值之间的相关性得出弹性模量。 FWD选择并反映了密西西比州典型路基土壤材料的十个竣工路基段。通过使用谢尔比管提取未受干扰的样品，并使用TP46协议在重复负载三轴仪中测试M_r。此外，还进行了其他常规实验室测试以对土壤进行分类。在建议的方法中，利用七个FWD传感器的挠度，通过正向计算方程式（假定为弹性半空间）来计算弹性模量E_1至E_7。针对M_r回归第一传感器模量E_1和平均偏移传感器模量E_（3-5）（即E_3，E_4和E_5的平均值），从而推进了两个模型进行M_r预测。通过使用E_1和E_（3-5），可以导出两个不同的弹性模量，其中两个中的较小者用作“设计弹性模量”。该方法的一个特点是，即使遇到路基剖面中明显的非均质性，中心传感器模量和偏移传感器模量的过程也可确保正确的路基特征。

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