杂多酸型层柱状阴离子粘土的合成表征与酸碱催化行为

合成了1：12系列Keggin结构磷钨钒杂多阴离子柱撑阴离子粘土，用元素分析，XRD和IR对产物的组成和结构进行了表征，考察了合成产物在异丙醇反应中的酸碱催化行为。研究表明，柱撑材料表面同时存在酸碱两类催化活性中心，但其催化性能明显优于粘土前驱体和相应杂多酸盐，且在考察的温度范围内，其酸性随温度的升高而增加。     

A modified creep index and its application to viscoplastic modelling of soft clays

Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.