岩体基本质量指标BQ图解法讨论

Discussion on Graphic Method of Rock Mass Basic Quality Index BQ

国标《工程岩体分级标准》在确定BQ时采用两个限制条件,给岩体基本质量直接分级带来不便。为了实现便捷分级,采用图解法解决这一问题。基于两种94国标下的BQ图解方法,给出修订版2014国标下的BQ分级表示图解法Ⅰ和图解法Ⅱ的作图方法。对于2014国标下的图解法Ⅰ,将有、无限制条件的情形进行对比,揭示限制条件的意义,发现2014国标对Kv上限进行限制的效果明显不如对Rc的上限进行控制的效果,可以考虑在保证分级精度的基础上将该限制条件舍去以简化分级过程;对于2014国标下的图解法Ⅱ,实现在任意给定Kv取值下的BQ-Rc曲线作图方法。通过工程实例进行计算,验证2014国标下的BQ图解法Ⅰ和图解法Ⅱ的合理性。

The national standard for engineering classification of rock mass adopts two restrictions in thedetermination of BQ, which make it inconvenient to directly classify basic quality of rock mass. In orderto realize convenient classification, graphic method is employed. The drawing methods for BQclassification of graphic method Ⅰ and graphic method Ⅱ in the revised 2014 national standard are givenbased on two graphic methods in 94 national standard. As for graphic method Ⅰ in 2014 nationalstandard, the comparison of the limited situation with the unlimited situation indicates that the effect oflimiting the upper limit of Kv is not as good as that of the upper limit of Rc, and the restrictions can beabandoned to simplify the classification process on the basis of ensuring classification accuracy. As forgraphic method Ⅱ, the BQ-Rc curve under any Kv is given so as to provide a preference for engineeringapplication. Graphic method Ⅰ and graphic method Ⅱ in 2014 national standard are proved reasonablethrough engineering projects.