基于大型三轴试验的砂卵石土本构模型比选

Comparison and Selection of Constitutive Models of Sandy Pebble Soil Based on Large Scale Triaxial Test

砂卵石土地层在成都平原地区分布广泛,但是砂卵石土作为大粒径粗粒土较难使用常规尺寸三轴仪进行试验。本文借助中国电建集团成都院自有的高压大型三轴仪进行数组三轴加载试验,并将应力应变曲线与采用Midas GTS进行模拟三轴试验得到的成果(分别采用摩尔库伦、修正摩尔-库伦以及硬化土小应变本构模型)进行对比。结果显示,考虑小应变效应的硬化土模型更适用于模拟砂卵石土的应力应变特征。并且该模型的主要参数可通过三轴试验(加载应力路径和卸载应力路径)和固结试验得到或间接推导,可推广用于砂卵石土为主要地层地区的地下结构设计。

Sandy pebble soil layer is widely distributed in Chengdu Plain,but it is difficult to use conventional size triaxial apparatus to test sandy pebble soil as large-size coarse-grained soil.In this paper,array triaxial loading tests are carried out with the help of high-pressure large scale triaxial apparatus owned by Chengdu Engineering Co.,LTD.The stress-strain curves are compared with the results of simulated triaxial tests by applying Midas GTS(Mohr Coulomb model,modified Mohr Coulomb model and small strain constitutive model of hardening soil are respectively applied).The results show that the hardening soil model considering small strain effect is more suitable to simulate the stress-strain characteristics of sandy pebble soil,moreover,the main parameters of the model can be obtained or indirectly derived by triaxial test(loading stress path and unloading stress path)and consolidation test,which can be extended to the design of underground structure in the area where sandy pebble soil is the main stratum.