基于分形理论的岩体原生节理分布特征研究——以长河坝水电站为例

Distribution Characteristics of Primary Joints of Rock Mass Based on Fractal Theory:Taking Changheba Hydropower Station as an Example

由于岩体内部结构面的分布规律具有随机性、复杂性的自相似的特征,可以运用分形理论对其进行研究。通过现场节理调查,描绘了待爆破区域原生节理的分布网络,并统计分析了节理迹长和倾角的概率分布模型;运用盒维数计算方法得出了结构面分布的分形维数D,讨论分形维数D与岩体的工程质量以及结构面分布之间的关系,实现了对岩体的工程性质以及不同尺度结构面的定量对比分析。结果表明:节理面的倾角和迹长分别服从正态和对数正态分布;江咀料场节理分布的分形维数D=1.315,响水沟料场节理分布的分形维数D=1.275,河口料场断层系的分维数D=1.164,可见分形维数D越大,结构面越发育,岩体的工程质量就越差;另外随着调查尺度范围的增大,分形维数D反而减小。研究结果可对分形理论在岩土工程质量评价及节理岩体的爆破块度预测等方面提供参考价值。

The distribution law of the internal structural plane of rock mass is random and complex.Because of its self-similar characteristics,it can be studied by fractal theory.The distribution network of primary joints in the area to be blasted was described by field joint investigation,and the probability distribution model of joint trace length and inclination angle were analyzed.The fractal dimension D of the structural surface distribution was obtained by using the box dimension calculation method.The relationship between the fractal dimension D and the engineering quality of the rock mass and the distribution of the structural plane was discussed,and the quantitative analysis of the engineering properties of the rock mass and the structural planes of different scales was realized.The results show that the inclination and trace length of joint surface obey normal and lognormal distribution respectively.Fractal dimensions D of the fault systems of the Jiangzui material field,Xiangshuigou material field and Estuary material field are 1.315,1.275 and 1.164 respectively.It can be seen that the larger the fractal dimension D is,the more developed the structural plane is,and the worse the engineering quality of rock mass will be.In addition,with the increase of the investigation scale,the fractal dimension D will decrease.The research results can provide reference value for fractal theory in geotechnical engineering quality evaluation and blasting fragmentation prediction of jointed rock mass.