重塑黄土一维应变实验粒子速度测试波形的拉格朗日分析

LAGRANGIAN ANALYSIS FOR A SET OF PARTICLE VELOCITY PROFILES MEASURED IN REMOLDING LOESS UNDER ONE-DIMENSIONAL STRAIN EXPERIMENT

  • 摘要: 利用57 mm口径一级轻气炮,飞片选用有机玻璃,对密度1.8 g/cm3、饱和度22%的重塑黄土,进行了一系列一维应变实验。通过在重塑黄土试样内布设多根Π形电磁粒子速度计,直接测得了多个粒子速度波形。该文详细介绍了一维应变条件下Lagrange分析方法的理论推导及求解过程,并对实测粒子速度波形进行了Lagrange分析,得到了加、卸载全过程的应力、应变波形。给出了3发不同压力条件下重塑黄土的应力-应变关系曲线,揭示了重塑黄土介质的本构滞回效应。并使用该应力-应变关系对试样内应力波传播过程进行了反分析,最后对Lagrange分析过程中遇到的问题进行了讨论。

     

    Abstract: Utilizing a single-stage light gas gun, plane shock-wave experiments were performed on the remold loess with a density of 1.8 g/cm3 and a saturation degree of 22%, in order to determine the dynamic behavior of the soil. The material of the projectile was PMMA. Wave motions were detected by four electromagnetic particle velocity sensors whose configuration were like П. The sensors were directly embedded into the remolding loess through the remolding process. The theoretical derivation and solution process of Lagrangian analysis based on one-dimensional strain was introduced in detail. The strain and stress profiles were determined through Lagrangian analysis of a set of particle velocity profiles measured in three typical experiments. The strain-stress relation with loading and unloading processes was obtained, which showed the hysteresis loop effect of the remolding loess. Based on this strain-stress relation, the particle velocity profiles were back analyzed. The difficulties encountered in the Lagrangian analysis were also discussed.

     

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