基于裂隙网络的消落带岩体劣化区域分布研究

经过十多年的145~175 m水位波动,三峡库区消落带碳酸岩岩体出现了明显的岩体劣化现象。根据岩溶岩体劣化形成机理与地表水―地下水的活动密不可分,本文首次提出了基于裂隙网络的连通性和水力边界条件的劣化岩体空间分析方法。利用增强Baecher模型、Levy―Lee分形裂隙模型、双变量fisher分布模型和双变量正态分布模型模拟随机裂隙位置和方位,构建定位裂隙与随机裂隙叠加的三维离散裂隙网络。通过裂隙连通性分析,确定连通区位置。考虑水力边界条件,利用相交分析圈定岩体劣化区空间展布情况。以龚家坊消落带岩体为例,验证了方法的有效性,并讨论了大型结构面和层面的重要作用。这一分析方法将有力推动三峡库区岩体劣化及防灾减灾相关工作。

Spatial Distribution Analysis of Degraded Karst Rock Mass in Fluctuation Zone Based on Fracture Network

After more than ten years of water level fluctuation between 145 m and 175 m above sea level, the carbonate rock mass in the fluctuation zone of the Three Gorges Reservoir has obviously deteriorated. According to the relationship between the formation mechanism of karst rock mass deterioration and the activity of surface water and groundwater, based on the connectivity of fracture network and hydraulic boundary conditions, a spatial analysis method for the distribution of deteriorated rock mass was proposed for the first time in this paper. The position and orientation of stochastic fractures were simulated by enhanced Baecher model, Levy-Lee fractal fracture model, bivariate Fisher distribution model, and bivariate normal distribution model. And a three-dimensional discrete fracture network was constructed to locate the superposition of definite fracture and stochastic fractures. Through the analysis of fracture connectivity, the location of the connected zone was determined. Considering the hydraulic boundary conditions, the intersection analysis was used to delineate the spatial distribution of deteriorated rock mass. Taking Gongjiafang as an example, the effectiveness of the method was verified, and the important role of large structural planes and layers was discussed. This analysis method will strongly promote the work of rock mass deterioration and disaster prevention and mitigation in the Three Gorges Reservoir Area.