Effect analysis of percussive compaction and dynamic compaction on roadbed reinforcement
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摘要: 在黄土地区陕西某高速公路段对原地基分别进行强夯与冲击碾压处理, 通过室内试验和现场原位测试, 对比了地基处理前后不同深度土体的物理力学指标(干密度、压缩模量与湿陷系数) 和微结构特征, 以及载荷板试验、触探试验、旁压试验结果, 研究了采用强夯和冲击碾压处理后黄土地基强度的形成机理、地基承载力变化、处理效果与有效影响深度。结果表明冲击碾压的有效影响深度在1.0~2.0 m, 在0~1.5 m处形成连续、均匀、密实的加固层; 强夯的有效加固深度达4.0 m, 有效影响深度在5.0~6.0 m, 在加固深度内湿陷性均被有效消除。Abstract: The highway bases of one section in the loess area of Shaanxi province were consolidated by percussive compaction and dynamic consolidation, the physical force indexes (dry density, constrained modulus and collapsibility coefficient) in different depths and the microstructure features of the loess were analyzed by soil engineering test in laboratory and original test, the results of plate loading test, cone penetration test and compressuremeter test were compared, the intensity forming mechanism of the loess roadbed and the changes, effects and valid influence depths of foundation bearing capacity in the loess area were analysed.Analysis result shows that the valid influence depth of dynamic consolidation ranges from 1.0 to 2.0 m, and successive, even, solid reinforcement layer is formed in the range between 0 and 1.5 m; for percussive compaction, the valid reinforcing depth reaches 4.0 m, the valid influence depths varies from 5.0 to 6.0 m, and the collapsibility is eliminated effectively in reinforcing depth. (2 tabs, )
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图 7 单桥试验比贯入阻力沿深度的变化
Figure 7. Change of penetration resistance of single cone test with depth
图 8 双桥试验锥尖阻力沿深度的变化
Figure 8. Change of conic node resistancy cofficient of double cones test with depth
图 10 动力触探试验击数沿深度的变化
Figure 10. Change of blow counts of dynamic sounding test with depth
图 11 旁压试验承载力沿深度的变化
Figure 11. Change of bearing capacity of compressu- remeter test with depth
表 1 湿陷性指标
Table 1. Collapsibility indices
桩号 湿陷等级 湿陷系数 自重湿陷系数 总湿陷量 自重湿陷量 压缩系数 压缩性 K171+413~K172+500 Ⅲ级自重湿陷 0.041 0.030 48.1 35.8 0.49 中等 K174+170~K176+890 Ⅱ级自重湿陷 0.027 0.009 32.8 5.6 0.31 中等 
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表 2 处理结果对比
Table 2. Comparison of treatment results
地基处理方法 分析指标 室内土工试验 触探试验 旁压试验 强夯压实 有效加固深度/m 4.0 4.0 4.0 有效影响深度/m 5.0~6.0 4.0~5.0 5.0~6.0 冲击压实 有效加固深度/m 0.5~1.0 0.5~1.0 0.5~1.0 有效影响深度/m 1.0~2.0 1.0~2.0 1.0~2.0
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