考虑变形滞后效应的高液限土路基模量反算方法
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长沙理工大学交通运输工程学院

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国家自然科学基金项目(51108049,51708071);交通运输部公路工程行业标准制修订项目(JTG-201507)


Modulus back-calculation method for high liquid limit soil subgrade
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Changsha University of Science & Technology

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National Natural Science Foundation of China (51108049,51708071); Revision Project of Highway Engineering Industry Standard System of Ministry of Transport (JTG-20507)

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    摘要:

    为了提高便携式落锤弯沉仪(PFWD)测定高液限土路基回弹模量的精度,考虑变形滞后效应对反算结果的影响,提出了一种基于Kelvin粘弹性模型和准静态动力分析反算模量的方法。通过现场试验,验证了新方法的有效性。研究结果表明:利用高液限土填筑的下路堤模量较低,在PFWD冲击荷载作用下,其顶面竖向位移峰值明显滞后于荷载峰值,且荷载-位移曲线非线性显著;基于线弹性模型的常规反算方法使得反算模量远大于实测模量,平均相对误差为52.5%;新方法能较好反映冲击荷载作用下变形滞后特征,反算相对误差仅为9.2%。随着路基模量增大,路基变形滞后效应不显著,常规方法和新方法反算结果相近,但前者仍远大于后者。研究成果可为高液限土路基施工质量控制提供参考。

    Abstract:

    In order to improve the accuracy of Portable Falling Weight Deflectometer (PFWD) in determining the resilient modulus of high liquid limit soil subgrade, and considering the influence of deformation lags effect on the back-calculation result. A new method for back-calculating the modulus was proposed based on Kelvin viscoelastic model and quasi-static dynamic analysis method. The effectiveness of the new method is verified by field tests. The results show that the measured modulus of the lower embankment filled with high liquid limit soil is lower and the peak vertical displacement of the top surface of the embankment obviously lags behind the peak value of the load under the impact load of PFWD. Furthermore, the load-displacement curve is significantly nonlinear. In addition, the conventional method based on linear elastic model makes the back-calculated modulus much larger than the measured modulus. The average relative error between back-calculated and the measured modulus reaches up to 52.5%. However, the new method can better reflect the deformation lag characteristics under impact load. The average relative error between them is only 9.2%. With the increase of subgrade modulus, the lag effect of the deformation is not significant. The back-calculating results of conventional and new methods are similar, but the former is still much larger than the latter. The modulus back-calculated by the new method can be used as the basis for construction quality control of high liquid limit soil subgrade.

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  • 收稿日期:2020-03-11
  • 最后修改日期:2020-03-19
  • 录用日期:2020-04-07
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