高放废物地下实验室北山预选区岩爆风险预测

结合世界各国经验以及当前国情,我国提出建立埋深500 m左右的地下实验室,用以开展高放废物地质处置前期的相关研究。根据北山预选区三个场址的地应力实测数据,分析发现在埋深600 m范围内地应力处于中等偏低的水平,但局部的应力集中增大了岩爆发生的可能,故开展场址的岩爆风险研究。综合北山岩体力学特性,选取隧道轴线与最大水平主应力方向垂直和平行两种情况,应用工程岩体分级标准判别法、Russense判别法和Turchaninov判别法分别对三个场址400~600 m埋深范围内的岩爆风险进行预测。结果表明:旧井和芨芨槽处隧道开挖均存在不同程度的岩爆风险,而新场处几乎无岩爆发生。从岩爆风险的角度来看,以新场作为地下实验室的场址最为安全。

Risk Prediction on Rockburstin Beishan Pre-Selected Area for Underground Research Laboratory of High-Level Radioactive Waste

Combining with the experience of other countries and the current national condition, our country put forward to establish an underground research laboratory with a buried depth of about 500m, to carry out studies of high-level waste disposal. Based on the in-situ stress results of Beishan area, it is found within 600 m depthall of three subareas are in the medium to low stress level. However, there is stress concentration somewhere, which increase the chance of rockburst. So it is necessary to analyze the risk of rockburst at these three subareas. By applying the least squares regression analysis to calculate the value of the stress within 400 m to 600 m depth, a risk analysis of rockburst is implemented with the method of engineering rock quality classification standard, Russense method and Turchaninov method. It is well known that the relationship between the tunnel axis and the maximum horizontal principal stress direction has significant influence on the stability of tunnel excavation. So the two extreme cases, in which the tunnel axis is perpendicular or parallel to the maximum horizontal principal stress, are considered during the risk analysis of rockburst. The result shows that there are different degrees of risk of rock burst at Jiujing site and Jijicao site, however, the Xinchangsite is much safer. In view of the lowest risk of rockburst, it is the best version to choose Xinchangsite as the ultimate site of underground research laboratory.