粉煤灰的基质吸力及非饱和特性研究

Research on matrix suction and un-saturated characteristics of fly ash

目前粉煤灰非饱和特性的工程描述多参考与其粒经类似的粉土,但两者由于颗粒级配和颗粒微观结构的不同,其工程非饱和特性方面的差异必然是存在的,目前尚没有见到这方面的研究成果。本文针对粉煤灰在非饱和特性研究方面的不足,首先采用Fredlund土水特征曲线测量仪试验研究了不同干密度、不同含水率等条件下粉煤灰土水特征曲线特征与基质吸力变化规律,探讨了粉煤灰脱湿过程与吸湿过程的非饱和性质差异。在此基础上,通过数值计算方法,分析探讨了粉煤灰非饱和特性对工程渗流、变形、稳定等计算分析成果的影响及程度。研究结果为:(1)在进行非饱和渗流计算时,采用粉煤灰的实测土水特征曲线才能较好的保证计算结果的可靠性,采用计算程序库中相应土的土水特征曲线来替代粉煤灰对结果将产生较大影响;(2)在进行稳定计算和应力应变分析时,用相应粉土来替代粉煤灰的土水特征曲线对计算结果整体影响不大,认为采用计算程序库中相应土的土水特征曲线来替代粉煤灰是可行的。

The engineering description of the un-saturated characteristics of fly ash refers to the silt with the similar structural properties. In fact,because of the difference grain size distribution and particle composition, there are inevitable differences on unsaturated engineering characteristics between them. However,there are few researches on this aspect. Hence,in this paper,the Fredlund soil-water characteristic curve(SWCC)test model is firstly chosen to study the soil-water characteristic curve and the matrix suction offly ash under the conditions of different dry density,water content and so on. And the un-saturated charac-ter differences of flay ash between dehumidification process and moisture absorption are discussed. On thisbasis,the influence of the un-saturated characteristics of fly ash on the calculation and analysis results ofengineering seepage,deformation is also discussed by using numerical calculation method. The following results are obtained:(1) A more reliable result will be get by using the measured SWCC of fly ash in theunsaturated seepage calculation. There will be a great influence to the result if use the corresponding SW-CC in the library;(2) in the stability calculation and stress strain analysis,the impact of using the SW-CC of the similar silt is not so big then SWCC of fly ash can be replaced.