三轴应力条件下粉土基泡沫轻质土压缩特性

Compression Characteristics of Silt-Based Foam Lightweight Soil under Triaxial Stress Conditions

摘要: 为探究粉土基泡沫轻质土在三轴应力条件下的压缩与剪切特性，本文通过不固结不排水(UU)三轴试验，系统研究了不同粉土掺量(0%, 25%, 50%)与围压(100 kPa, 300 kPa, 500 kPa)对材料应力–应变行为、抗剪强度及破坏模式的影响。结果表明：粉土基泡沫轻质土的应力–应变曲线呈现典型的应变硬化或软化特征，可分为弹性、硬化/软化和压密三个阶段；围压升高显著提升峰值应力与残余强度，而粉土掺量增加则导致黏聚力与内摩擦角显著下降，掺量50%时黏聚力降幅达78.8%；破坏模式随围压与掺量变化由剪切破坏向压密破坏过渡。抗剪强度参数远高于现行规范推荐值，表明材料具有良好的工程适用性。研究结果可为粉土基轻质土在路基工程中的设计与应用提供理论依据。

Abstract: To explore the compressive and shear characteristics of silt-based foam lightweight soil under triaxial stress conditions, this paper conducts a non-consolidated and non-drained (UU) triaxial test. The effects of different silt dosages (0%, 25%, 50%) and confining pressures (100 kPa, 300 kPa, 500 kPa) on the stress-strain behavior, shear strength and failure mode of materials were systematically studied. The results show that the stress-strain curve of silt-based foamed lightweight soil presents typical strain hardening or softening characteristics, which can be divided into three stages: elastic, hardening/softening and compaction. The increase in confining pressure significantly enhances the peak stress and residual strength, while the increase in silt content leads to a significant decrease in cohesion and internal friction angle. When the content is 50%, the reduction in cohesion reaches 78.8%. The failure mode transitions from shear failure to compaction failure with the variation of confining pressure and dosage. The shear strength parameter is much higher than the recommended value in the current specification, indicating that the material has good engineering applicability. The research results can provide a theoretical basis for the design and application of lightweight soil based on silt in subgrade engineering.