基于图解法的BQ分级限定条件及计算公式研究

《工程岩体分级标准》(GB/T 50218—2014)修改了原标准GB 50218—1994中的BQ(basic quality)分级指标计算公式,但其两个限定条件(岩石饱和单轴抗压强度和岩体完整性系数)没有进行同步修正.通过大量数据研究发现,直接用受岩石饱和单轴抗压强度(R_○c)和岩体完整性系数(K_○v)限定条件折减后的数据进行定量计算,多会导致定性与定量计算结果不吻合.本文对限定条件进行修正,并基于简化的图解法进行分析,得出R_○c限定条件的影响范围较广泛,则以数据库中新增54组数据为样本,由R_○c限定条件折减的数据进行回归分析建立新的计算公式.将得到的修正后的限定条件和新的区段计算公式,依托实际工程数据进行验证.结果表明,本文修正的限定条件和提出的计算公式提高了定性分级与定量分级的吻合度,得到了更准确的分级结果.

Study on Limited Conditions and Calculation Formula of BQ Classification Based on Graphic Method

The calculation formula of BQ (basic quality) classification index in GB 50218—1994 is modified in the revised Standard for Engineering Classification of Rock Mass(GB/T 50218—2014), but its two limiting conditions(saturated uniaxial compressive strength of rock and rock mass integrity coefficient)were not modified simultaneously. Through a large number of data studies, it is found that the calculation results are inconsistent with the qualitative and quantitative calculation results when the data are directly reduced by R_○c and K_○v constraints. Therefore, the limited conditions are modified and analyzed based on simplified graphical method. According to the analysis results that are widely affected by R_○c constraints, 54 sets of new data in the database are taken as samples, and a new calculation formula is established by regression analysis of the data reduced by R_○c constraints. The revised limit conditions and new section calculation formula obtained are analyzed and demonstrated on the basis of actual engineering data. The results show that the revised limited conditions and the calculation formula proposed in this study improve the agreement between the qualitative classification and the quantitative classification, and a more accurate classification result is obtained.