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以LG-8200M型室内大型直接剪切仪为基础,针对非饱和粉土的抗剪强度及变形特性问题展开实验研究.研究结果表明:(1)低含水质量分数的重塑非饱和粉土试样在高垂直压力下剪切峰值不明显,呈现明显的应变硬化特性,在低垂直压力(0.1 MPa)下剪应力-剪切位移关系存在剪切峰值,达到峰值后曲线趋于平缓.(2)相同含水质量分数的重塑非饱和粉土试样,其剪切面抗剪强度随法向应力的增大而提高,随剪切速率的增大而降低,剪切速率每增加0.4 mm/min,其抗剪强度减少约20%~30%.(3)不同含水质量分数的重塑非饱和粉土试样,其抗剪强度指标(c,φ)随含水质量分数的增大呈现先升高后减小的变化趋势,且含水量超过临界值后,粉土的抗剪强度会急剧衰减,内摩擦角比粘聚力衰减速度更为明显.
Based on LG-8200M indoor large-scale direct shearing instrument, the experimental research on the shear strength and deformation characteristics of unsaturated silt is carried out.The results show that: (1) the remodeled unsaturated silt with low water content The peak shear stress is not obvious under high vertical pressure, showing obvious strain hardening characteristics. Under the condition of low vertical pressure (0.1 MPa), there is a shear peak in the relationship between shear stress and shear displacement. ), The shear strength of the modified unsaturated silt samples with the same water content increased with the increase of normal stress and decreased with the increase of the shear rate. For every increase of the shear rate by 0.4 mm / min, the shear strength is reduced by 20% ~ 30%. (3) The shear strength index (c, φ) of the remolded unsaturated silt samples with different water content shows the increase with the increase of water content After increasing and decreasing, the shear strength of silt will decrease sharply when the water content exceeds the critical value, and the internal friction angle declines more rapidly than the cohesion decay rate.