基于BQ系统的阿拉善巴彦诺日公NRG01号钻孔岩体质量评价

ROCK MASS QUALITY ASSESSMENT OF BOREHOLE NRG01 IN BAYANNUORIGONG ALXA BASED ON BQ-SYSTEM

高放废物深部地质处置目前受到世界各国的高度重视,处置库围岩岩体质量评价是高放废物处置库选址的关键问题之一。文章基于BQ系统对我国高放废物地质处置库阿拉善预选区巴彦诺日公NRG01号钻孔进行了岩体质量评价。NRG01号孔钻孔资料丰富,采用岩芯编录、波速测井、水压致裂地应力测量及岩石波速测试、单轴压缩试验等多种方法手段相结合的方式获取了BQ评价系统中的各个参数。评价过程中,综合考虑了岩体坚硬程度、完整程度及地下水、软弱结构面、初始地应力等因素对围岩稳定的影响。根据计算的[BQ]值对岩体质量进行评价并与RQD评价结果进行对比。评价结果表明,NRG01号孔岩体质量较好,Ⅰ级和Ⅱ级岩体占90%,410~500 m的岩体范围可作为处置库建设的目标岩体。[BQ]值与RQD值所得的岩体质量评价结果一致性良好,但由于BQ系统考虑的影响因素更为全面,评价结果更为精细。本次评价可为巴彦诺日公地段高放废物地质处置库场址比选及处置库目标岩体选择提供依据。

High level radioactive waste is the inevitable product of nuclear power development. The whole world has paid more attention to the safety disposal of the waste so as to maintain the sustainable development of nuclear power. At present,deep geological disposal has become a recognized permanent disposal method of high level radioactive waste,and surrounding rock mass quality assessment is the key to the selection of high-level waste disposal repository. Alxa is a pre-selected area for high-level radioactive waste disposal in China. Based on BQ-system,the rock mass quality of Bayannuorigong borehole NRG01 in Alxa region was assessed. BQ-system is a comprehensive rock mass quality assessment method, which take the rock mass hardness and integrity into consideration. The borehole data of NRG01 is rich. The evalution parameters of BQ-system were obtained by different methods and techniques such as core logging,wave velocity logging,hydrofracturing in situ stress measurement, rock ultrasonic wave velocity measurement and uniaxial compression test. The BQ value was calculated using those parameters. Then,according to the effects of ground water,weak structural surface and initial crustal stress,the BQ value was modified. The modified [BQ] value was used to classify the quality of rockmass into five categories. Result shows that the rock mass quality of borehole NRG01 is good,about 90%rock belong to Ⅰ and Ⅱ category,the rock mas range of 410 ~ 500 m can be regarded as the target rock for the construction of the repository. The qualitive conclusion of BQ-system was compared with that by RQD index. RQD index is simple and straightforward which is the most commonly used indicator for rock mass quality assessment.Comparison result showed that two methods have good coherence. However,BQ-system take more factors into consideration,therefore it is more comprehensive and refined. Evaluation results can provide reference for siting the repository of high-radioactive waste disposal and the the selection of the target rock.