地基应力对土基剪切波速的影响建模

地基剪切波速与土基密实程度直接相关,广泛应用于场道地基压实质量评估。现有剪切波速测试模型主要考虑干密度、含水率等因素,忽略了土基应力对剪切波速的影响,导致利用剪切波速测定高深度及大应力状态土层力学性能时存在较大误差。本文设计了土基应力与剪切波速试验装置,开展了变应力条件下粘土和砂土两种土样的剪切波速试验,研究了土颗粒应力传播及应力损失条件下剪切波速变化特性,建立了基于应力扩散的地基土剪切波速与土中应力相关性模型,并对模型计算结果与现场实测数据进行对比分析,以验证模型的有效性。结果表明:土基剪切波速随应力的增大总体呈增大趋势;应力相等条件下,土体剪切波速随测试土层厚度的增大而下降,地基应力对土基剪切波速影响显著。

Modeling Study on Influence of Foundation Stress on Shear Wave Velocity of Subgrade Soil

The foundation shear wave velocity is directly related to the soil compactness, and is adopted to evaluate the pavement subgrade compaction quality generally. The dry density and water content are considered in the existing test model of shear wave velocity while foundation stress is not considered, which causes amount of errors in soil mechanical property testing under the condition of high depth and large stress using shear wave velocity. In this paper, test apparatus of foundation stress and shear wave velocity is designed,and change features of shear wave velocity under conditions of stress spreading and stress lossing among soil particles are studied by testing shear wave velocity of clay and sandy soil with changing stress. The correlation model of foundation stress and shear wave velocity based on stress diffusion is built. The model calculating consequence and field testing data are contrastively analyzed, and the effectiveness of model is confirmed. The results show that the shear wave velocity of foundation increases with the increasing of soil stress, the velocity decreases with the increasing thickness of test soil layer in condition of identical stress, and the soil shear wave velocity is significantly affected by foundation stress.