贵阳既有地基红黏土蠕变特性试验研究

Experimental study on creep behavior of red clay of existing foundation in Guiyang City

为了准确地掌握喀斯特发育地区岩溶作用对红黏土的结构影响,以及红黏土地基的蠕变特性,以贵州铝厂既有地基红黏土为研究对象,采用分别加载法进行了室内单轴蠕变固结试验和三轴蠕变试验,建立单轴蠕变经验方程以及Singh-Mitchell模型。结果表明:贵州铝厂红黏土的单向固结有线性规律,表现在t/ε和t存在高度的线性相关性,其单向固结经验方程中的一个参数b可用于预测试样在单向固结下的最终沉降量。所建立的Singh-Mitchell三参数的蠕变模型较好表达了试验土体在25%~100%偏应力水平范围内的应力-应变-时间三者的关系特性。同时,SEM图片表明随着竖向压力不断地增大,单轴固结试验下该红黏土的孔隙面积和微观颗粒数减小,颗粒面积变大,三维孔隙率增加,说明能用孔隙变化的微观规律来反映宏观现象。

In order to further understanding the creep characteristics of red clay in the existing foundation,a uniaxial creep consolidation and triaxial creep tests were carried out in the laboratory respectively,with samples collected from the Guizhou Aluminum Plant,Guiyang City.Then a uniaxial creep empirical equation and Singh-Mitchell model were established based on the test data.The results show that under unidirectional consolidation there is a linear relationship between t/s and t,with a very high correlation coefficient.Because of the high correlation,the parameter b of the uniaxial creep equation can be used to assess total settlement in an uniaxial consolidation condition.The Singh-Mitchell three-parameter creep model established can better express the stress-strain and time relation of tested soil in the range of 25% to 100% deviatoric stress.At the same time,the SEM images show that with the increase of vertical pressure,the pore area and the number of micro particles of the red clay decrease, while the particle area gets larger,and the three-dimensional porosity grows in the uniaxial consolidation test,indicating that the change of the clay particle pores on a micro scale can be used to explain the macro phenomenon.