New mixed boundary true triaxial loading device for testing study on 3-D stress-strain-strength behaviour of geomaterials

Abstract

A brief review of the true triaxial apparatuses (TTA) developed in the past and their advantages and limitations are presented. Considering the limitations of previous designs, a new true triaxial loading device which provides mixed boundary conditions for a TTA is introduced. A three-dimensional finite element (FE) modelling study is carried out on the stress and strain distribution of a soil specimen subjected to loading from two different loading devices. It is found that the stresses and strains of the soil specimen subjected to loading from the new sliding plates are far more uniform than those subjected to loading from non-sliding plates with preset gaps. Finally, the applications of the present TTA with the new loading device for testing studies on a completely decomposed granite soil and a geofoam are introduced. Typical results are presented and discussed. 介绍一个新型土力学真三轴仪加载装置-刚性滑板加柔性面的混合边界加载装置。利用三维有限元模型分析两种不同加载装置对土样应力应变分布的影响。分析表明新的刚性滑板加载设计使土样中的应力应变更加均匀。最后讨论了一组完全风化花岗岩土和一组土工泡沫材料的真三轴试验结果。完全风化花岗岩土的排水剪切试验在在等p’,不等b条件下进行。土工泡沫材料的试验在等b,不等p’条件下进行。试验结果表明完全风化花岗岩土的最大偏应力随b值增加而减小。土工泡沫材料摩擦角为负值,具有屈服点随p’值增大而减小的特性。