基于干湿循环与三维条件下污泥固化土邓肯-张模型研究

为研究城市污泥固化土作为路基填料时其在复杂应力状态下的力学特性，通过GCTS真三轴试验仪对城市污泥固化土进行不固结不排水试验，探讨其在不同干湿循环次数和中主应力比条件下的应力-应变特性和抗剪强度指标变化规律，并在三维条件下对邓肯-张模型进行了双重修正。研究结果表明：当干湿循环次数和围压一定时，污泥固化土的结构屈服应力随着中主应力比的增大而增大；当中主应力比和围压一定时，污泥固化土的结构屈服应力随着干湿循环次数的增加而降低，且干湿循环次数为3时降幅最大，干湿循环次数大于5之后土体结构屈服应力降幅较小；此外，对比污泥固化土的真三轴试验曲线与邓肯-张模型预测曲线，发现理论曲线与试验曲线存在一定差异，而通过考虑中主应力比、干湿循环次数和中、小主应力差作用的影响对污泥固化土邓肯-张模型进行2次修正，使得到的邓肯-张模型预测曲线与真三轴试验曲线基本一致，该预测曲线可准确反映污泥固化土的真实受力状态，可为其在路基工程中的应用、施工提供理论指导和预测分析。

Duncan-Chang Model of Sludge-solidified Soil Based on Dry-wet Cycles and Three-dimensional Conditions

In this study, the mechanical properties of urban sludge-solidified soil as a roadbed filler under complex stress conditions were investigated. A GCTS triaxial tester was used to perform unconsolidated and undrained tests on urban sludge-solidified soil. The stress-strain characteristics and shear strength index variations of the urban sludge-solidified soil under different dry-wet cycles and intermediate principal stress ratios were determined, and the Duncan-Chang model was double-corrected under three-dimensional conditions. The results show that when the number of dry-wet cycles and confining pressure are constant, the structural yield stress of sludge-solidified soil increases with an increasing ratio of intermediate principal stresses. When the principal stress ratio and confining pressure are constant, the structural yield stress of the sludge-solidified soil decreases with an increasing number of dry-wet cycles. When the number of dry-wet cycles is three, the decrease is most significant, but when it exceeds five, the structural yield stress of the soil decreases slightly. In addition, a comparison between the triaxial test curve and Duncan-Chang model prediction curve indicates a slight difference in results. However, based on the medium principal stress ratio, number of dry-wet cycles, and difference between the medium and small principal stresses, the Duncan-Chang model was double-corrected. The Duncan-Chang model predicted curve is consistent with the triaxial test curve. This prediction curve precisely reflects the actual stress state of sludge-solidified soils and provides theoretical guidance and predictive analysis for its application and construction in roadbed engineering.