取土器几何尺寸对饱和软黏土样结构的扰动研究

Disturbance of Saturated Soft Clay Samples′ Structure by the Geometrical Size of Soil Samplers

基于颗粒流软件模拟,以吹填淤泥为例,分析了取土器的内径、切角、壁厚等尺寸参数对高黏性软土微观动力学特性的影响;通过分层方法,比较了7组土样层间颗粒特征拐点的运动行为。模拟结果表明:土样的颗粒在底部形成对流位移场,对流处上方颗粒主要受拉膨胀,对流处下方颗粒主要受压收缩,由此造成孔隙率的规律变化和层理的弯曲变形。7组参数对应土样的孔隙率曲线与初始孔隙率曲线的交点同颗粒位移场的对流位置存在协同关系。土样层理表现为向下弯曲变形,层间颗粒位移行为存在特征拐点,拐点之间颗粒扰动行为不明显;反之,颗粒扰动行为较大,这种变形特征可拟合为下开口的旋转抛物面,且曲面方程的曲面形状拟合系数a值能初步评估7组土样的扰动程度。层间特征拐点的连线可再拟合为旋转抛物面,抛物面体积与土样体积的比值可用来评估土样的原状性。

Based on the simulation of particle flow software, this paper analyzes the effects of size parameters such as inner diameter, cutting angle and wall thickness of samplers on the micro-dynamic characteristics of high-viscosity soft soil.The stratification method was used to compare the motion behavior of characteristic inflection points of particles within layers between the seven groups′ soil samples. The simulation results show that the particles of the soil samples form a convective displacement field at the bottom, and that the particles above the convection are mainly subject to tensile expansion, while the particles below the convection are mainly compressed and contracted, thereby causing regular changes in porosity and bending deformation of the bedding.The intersection of the porosity curve of 7 groups' soil samples and their initial porosity curves has a synergistic relationship with the convection position of the particle displacement field. The soil layer is characterized by downward bending deformation. There is a characteristic inflection point in the displacement behavior of the interlayer particles. The particle disturbance behavior between the inflection points is not obvious. On the contrary, the particle disturbance behavior outside the inflection points is large. This deformation feature can be fitted to the lower-opening rotating paraboloid. The value of the surface equation can be used to initially assess the degree of disturbance of the 7 groups of soil samples. The line connecting the inflection points of the layers can be refitted to a rotating paraboloid.The ratio of the parabolic volume to the volume of the soil samples can be used to assess the undisturbance of the soil sample.