城际铁路水泥改良黄土填料力学特性

Mechanical Properties of Cement-Improved Loess Filler for Intercity Railway

为揭示城际铁路水泥改良黄土路基填料力学特性变化规律,通过室内试验研究了水泥剂量、压实系数、养护龄期对水泥改良黄土路基填料力学特性的影响规律,优化设计改良黄土填料水泥剂量。研究表明,压实系数0.92下2%(质量分数,下同)水泥剂量改良黄土试件的7 d抗压强度满足规范值,但浸水后试件破损;水泥剂量≥3%的改良黄土试件浸水后完整,水泥剂量增加1%,28 d抗压强度和劈裂强度至少分别平均增长12.3%、17.0%;压实系数提高0.01,改良黄土28 d抗压强度和劈裂强度分别至少增长了5.4%、8.0%;改良黄土前期力学强度增长速率明显大于后期强度增长速率,水泥剂量≥3%的改良黄土试件的7 d抗压强度和劈裂强度分别约是其对应极限强度的61%、45%。为保证路基强度和承载力,考虑经济效益,建议基床底层以下路堤水泥剂量为3%,压实系数为0.95;建议基床底层路堤水泥剂量为4%,压实系数为0.98。

In order to reveal the change law of the mechanical properties of the cement-improved loess subgrade fillers on the intercity railway,the influence of cement dosage,compaction coefficient,and curing age on the mechanical properties of the cement-improved loess subgrade fillers were studied through laboratory tests,and the dosage of the improved loess filler cement was optimized.The research shows that the compression strength of 2%(mass fraction,the same below)cement dosage improved loess test piece at 7 d under the compaction coefficient of 0.92 meets the standard value,but the test piece is damaged after soaking;the improved loess sample with cement dosage≥3%is complete after soaking,and the cement dosage increases by 1%.28 d compressive strength and splitting strength increase at least 12.3%and 17.0%on average,respectively.The compaction coefficient increases by 0.01,the compressive strength and splitting strength of the improved loess increase by at least 5.4%and 8.0%.The strength growth rate is significantly higher than that of the later stage.The compressive strength and splitting strength of the improved loess specimen with cement dosage≥3%were about 61%and 45%of their corresponding ultimate strengths,respectively.In order to ensure the strength and bearing capacity of the subgrade,the cement dosage of the embankment below the foundation bed is recommended to be 3%and the compaction coefficient is 0.95.The cement dosage of the embankment to the bottom of the foundation bed is recommended to be 4%and the compaction coefficient is 0.98.