北山预选区新场地段岩体节理几何特征及评价

准确分析和评价BS17,BS18和BS19钻孔周边岩体节理几何特征,是我国高放废物处置北山预选区新场地段场址筛选及适宜性评价的重点内容和关键步骤之一。通过现场调查、数理统计和概率分析等方法,对该地区的岩体节理几何特性进行研究,结果表明:(1)各钻孔均发育4个节理优势组,尤以NE向和NW向最发育;(2)节理倾角以陡倾角的剪节理为主,节理产状服从正态分布函数,节理间距可用负指数函数进行有效拟合;(3)节理平均间距宽,迹长长,中点面密度小。基于岩体节理在高放废物处置库工程安全运行中的重要性。采用JSR法对岩体节理发育特征进行综合评价,发现新场地段3个钻孔周围岩体节理发育程度轻微、区域差异性小、岩体完整性好,断层对其两侧岩体的节理发育有促进作用,研究结果可为北山预选区处置库场址筛选和场址适宜性评价提供必要的数据支持。

Geometric features of joints and quality evaluation of rock mass in Xinchang section，Beishan

Accurate analysis and evaluation of the geometric features of joints around BS17，BS18 and BS19 boreholes are the major task of site selection and site suitability evaluation of Xinchang section at Beishan，a candidate area in China. Site investigation，mathematical statistics and probability analysis were applied to study the geometric features of joints. 4 joint sets were observed in three boreholes，and the dominant orientations for joints are NE and NW. Joints are mainly shearing and steep dip and obey the normal distribution function. The spacing of joints is a negative exponential function. Wide spacing，long trace length and small trace midpoint density are the main characteristics of Xinchang section. Considering the importance of joints in high-level radioactive repository， method was applied to evaluate the quality of rock mass. The results indicate that the joints of rock mass are little developed and that the differences between the regions are small. Hence，the integrity of rock mass is good. In addition，the existence of faults may promote the joints development along the two sides of the fault in rock mass. The research and evaluation of joints provided important data support for repository site selection and site suitability evaluation