凝灰岩遇水分解过程微细观结构参数敏感性分析

Sensitivity Analysis of Microstructural Parameters of Tuff During Water Decomposition

为了研究凝灰岩遇水分解过程微细观结构参数,确定描述分解过程的敏感指标,开展了微细观结构试验和微细观结构参数敏感性分析。首先采用微细观结构试验方法测定原状未分解和不同分解时间的凝灰岩的微细观结构参数,然后利用敏感性分析方法研究各微细观结构参数对分解时间的敏感性。结果表明:随着分解时间的增大,颗粒的圆度值越来越小,颗粒分布分维数越来越大,孔隙度逐渐增大,孔隙分布分维逐渐增大,欧拉数逐渐减小;在遇水分解过程,颗粒的形状趋于圆形的程度降低,颗粒团聚的程度降低,颗粒凌乱化程度增大,岩石结构愈加松散,凝聚趋势减弱,宏观上表现为岩石的强度降低;颗粒分布分维和孔隙分布分维对分解作用时间不敏感,不利于测度分析变化情况,而欧拉数过于敏感,微小的分解时间变化将带来较明显的欧拉数变化,指标分析结果容易产生较大的误差,因此可选用孔隙度作为凝灰岩分解过程的敏感指标。

In order to analyze the microstructural parameters of tuff during water decomposition and determine the sensitive indexes to describe the decomposition process, microstructural tests and sensitivity analysis of microstructural parameters were carried out. Firstly, the microstructural parameters of tuff undisturbed and at different decomposition times were determined by the microstructural test method. Then, sensitivity analysis was used to analyze the sensitivity of microstructural parameters to the decomposition time. The results show that with the increase of decomposition time, the roundness value of particles decreases, the fractal dimension of particle distribution increases, the porosity increases, the fractal dimension of pore distribution increases, and the Euler number decreases. During the decomposition process on contact with water, the degree of particle shape tends to be round, the degree of particle agglomeration decreases, the degree of particle disorder increases, the rock structure becomes looser, the trend of agglomeration becomes weak, and the strength of rock decreases dramatically. The distribution fractal dimension of particle and pore are not sensitive to decomposition time, which is not conducive to measure analysis. The changes of the Euler number are very sensitive, small weathering time change will bring more apparent Euler number change, index analysis results to a larger error, so can choose porosity as a sensitive index in the process of decomposition of tuff.