ISSN 1000-3665 CN 11-2202/P

    江北机场高填方夯后碎块石土剪切力学性质研究

    A study of the shear mechanical properties of high-filled gravel-block soil after dynamic compaction near the Jiangbei airport

    • 摘要: 重庆江北机场高填方边坡高度普遍为60~120 m,填料主要为砂、泥岩混合料,含石量非常高,也存在较多大粒径块石。对夯后填土开挖4 m深(强夯填土分层厚度)的大探坑,测试夯后填土的密度、物质组成,并拍照获取现场图像。通过筛分测试及图像处理技术,得到了夯后填料的级配曲线及结构特征。从工程尺度,将夯后填料粒径小于60 mm的视为胶结物,通过重塑样直剪试验测试标定其剪切性质。基于现场照片的图像分析,建立符合工程实际的夯后填土大尺度颗粒流数值模型,考虑粒径60 mm以上的碎块石的真实分布,模拟研究了江北机场高填方体夯后高含石量填料的剪切变形、损伤演化及剪切强度特征,揭示了夯后填料临近峰值及峰后剪应力与法向位移波动特征、大块石及含石量对剪切带分叉及绕石和峰后剪切应力跌落的影响规律。

       

      Abstract: The high-filled slopes near the Chongqing Jiangbei Airport are generally 60-120 m high, and the fill is mainly the sand-mudstone mixture, with high stone content and large-size block stone. Exploratory pits were excavated to 4 m deep to measure the density and composition of the fill and get the scene images. Combining grading test with image processing technology was carried out, and the whole grading curve of the fill was obtained. From the engineering scale, the gravel-block soil with the size less than 60 mm after dynamic compaction was taken as the soil particles in the numerical simulation. The shear properties of the soil were tested with the direct shear test with the remolded samples. Based on the photo analysis, numerical models of large-scale particle flow of fill were set up. The grained stones’ actual distribution was considered in the numerical test. The shear behavior, damage evolution and shear strength of the fill in near the Jiangbei Airport were simulated. The results show the fluctuation characteristics of shear stress and normal displacement when the fill reaches and exceeds the peak value. The effects of large stone and stone content on the shear band bifurcation and post-peak shear stress dropping are also discussed.

       

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