地下坑道轮廓超挖的随机特征

The Random Character of the Over-Excavation of Sap Surrounding Rock Outline

首先分析了坑道轮廓超欠挖的分布曲线,发现该曲线在形状上具有直观自相似性;然后收集了大量坑道超欠挖数据.根据国家工程岩体质量分级标准,将收集到的超欠挖数据所在坑道的围岩分为Ⅱ,Ⅲ,Ⅳ类,相应地将超欠挖数据分为3组.画出每一组数据的个数与数据值的双对数图,利用最小二乘法拟合出各组数据各自线性回归方程,发现3组数据各自的线性相关程度很好,都具有良好的线性关系,因此证明了Ⅱ,Ⅲ,Ⅳ类围岩坑道的超欠挖数据符合分形分布规律.进一步计算了各组数据的分数维,得出在某些条件下随着围岩类别的增大,超欠挖数据分布的分数维减小的趋势.

<Abstrcat>The distribution curve of the over-excavation and under-excavation of sap outline was analyzed. It was found that the curve was intuitively self-semblable. A lot of data of the over-excavation and the under-excavation of sap outline were collected. Based on engineering rock-mass quality classification standard, the rock-mass quality of the above mentioned sap was divided into three types, namely, Types Ⅱ,Ⅲ and Ⅳ. The collected data were also divided into three groups. The double logarithm sketch of each group's number of data and their values was drawn. After the linear regression equation of each data group was figured out through the least double multiplication, it was found that the linearity correlation degree was very high. Therefore, the distribution of the over-excavation and under-excavation value of the saps outline located in Types Ⅱ,Ⅲand Ⅳ rock mass conformed to fractal distribution. And the fractal dimension of the curve of each group of data distribution was calculated. It was found that the fractal dimension of the curve of over-excavation and under-excavation value increased when the quality of surrounding rock get poorer under certain conditions. A foundation for the analysis of the stability of tunnel structures and the random research model of the stability of tunnel structures was established with the above-mentioned results.