Large-scale triaxial tests on unit cell of composite soil with cement-soil columns under static loading
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摘要: 水泥土桩法作为一种常用的软土加固方法,可有效提高地基承载力、减小沉降。国内外众多学者对水泥土桩复合地基进行了相关研究,但由于现场试验和模型研究中其应力状态不够明确,无法正确分析其力学特性。采用大型三轴试验研究静荷载下水泥土桩复合单元体的力学特性,获得了置换率和围压对其峰值强度与残余强度的影响。最后提出了改进的水泥土桩复合体等效黏聚力经验公式,可为水泥土桩复合地基的设计提供参考。Abstract: The cement-soil column, as one of the commonly-used ground improvement methods, can effectively improve the bearing capacity of foundation and reduce settlement. There have been many researches focused on this topic. However, the stress state of the composite soil is not clear in field and model tests, therefore, its real mechanical behavior is difficult to be obtained. A series of large-scale triaxial tests are conducted to investigate the unit cell of the composite soil with cement-soil columns under static loading. The influences of replacement ratio and confining stress on the peak and residual strengths are gained. An empirical method for calculating the equivalent cohesion of the composite soil is proposed, providing a reference for the design of composite foundation with cement-soil columns.
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图 3 不同围压下水泥土桩复合单元体应力-应变关系
Figure 3. Stress-strain curves of specimens under different confining stresses
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图 4 不同置换率下水泥土桩复合单元体应力-应变关系曲线
Figure 4. Stress-strain curves of specimens with different replacement ratio
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图 6 水泥土桩复合单元体强度随围压的变化
Figure 6. Variation of strength of unit cell with confining stress
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图 7 水泥土桩复合单元体强度随置换率的变化
Figure 7. Variation of strength of unit cell with replacement ratio
表 2 等效黏聚力计算结果
Table 2 Calculated results of equivalent cohesion
置换率/% 试验结果/kPa 式（2）/kPa 式（5）/kPa 偏差 式（2） 式（5） 11.1 25.0 57.9 25.3 0.43 0.99 16.0 39.0 80.4 38.2 0.49 1.02 21.7 55.3 106.5 55.8 0.52 0.99 平均值 0.48 1.00 
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