取土器贯入扰动变形规律透明土试验研究

Tests on transparent soil for soil disturbance deformation induced by sampler penetration

在岩土工程取样过程中,取土器贯入会引起土样扰动变形,造成土样物理力学性质的改变。为了研究取土器贯入过程中土体扰动变形特性及其影响因素,基于透明土及PIV技术,进行了不同尺寸、不同贯入速率的取土器贯入试验,得到了取土器贯入过程中土体扰动变形场的分布特性及规律。模型试验结果表明:土体扰动变形随着贯入深度增大而增大,管内土体表现为向上的隆起变形,在深度方向最大变形基本位于深度20 mm处;增大取土器内径能有效减小轴线处土体扰动变形,但减小幅度随着内径的增大而减小;增大取土器贯入速率不能有效地减小结构性较弱的砂性土样的扰动变形。

The soil disturbance deformation induced by sampler penetration has a significant influence on the physical and mechanical properities of soil in soil investigation engineering. A series of small-scale model tests with different sampler diameters and penetration rates are conducted to investigate the disturbance deformation characteristics of soil and the influence factors during sampler penetration by using transparent soils and PIV(particle image velocimetry) technique. The test results show that the disturbance deformation of soil increases with the depth of sampler penetration, and the disturbance deformation of soil in sampler is mainly upheaval, and the maximum upheaval deformation occurs at the depth about 20 mm. Increasing the sampler diameter can reduce the disturbance deformation of soil at sampler centerline effectively, but the reduced magnitude of deformation decreases with the sampler diameter. The sampler penetration rate has no effect on the disturbance deformation of non-structured soil.