Three kinds of conventional evaluation systems were applied to evaluate the quality of unloading rock mass, and rock mass mechanics parameters in original and unloading condition were calculated respectively, so the deficiencies of conven-tional evaluation systems in evaluation of unloading rock mass quality was made clear. Accordingly, we put forward a new quality evaluation system of USMR method that is suitable for unloading rock mass. The presented system considers the basic rock prop-erties included in normal RMR method, such as rock block condition, structural plane condition and spacing, groundwater, and also the slope dip and structural plane dip, relationship between slope proneness and structural plane proneness; besides, the factors of rock mass degradation such as excavation method, unloading damage and slope shape are taken into account as well. The cm value calculated by USMR is smaller than that of three conventional methods, which is accord with the actual condition. The results have certain guiding significance to rock mass stability analysis of high slope excavation engineering.%采用3类常规评价体系对卸荷岩体质量进行分析评价，并求解原态和卸荷态岩体力学参数，分析常规评价体系在评价卸荷岩体质量中存在的不足。有针对性地提出了适用于卸荷岩体的质量评价体系USMR法。该法不仅考虑了岩块条件、结构面条件和间距、地下水等RMR法包含的岩体基本性质，还考虑了坡面倾角与结构面倾角、坡面倾向与结构面倾向的关系，另外对开挖方法、卸荷损伤、边坡形态等使岩体质量劣化的因子进行了分析评价。基于USMR法所得的cm 值小于常规方法，符合实际情况。所得结论对高边坡开挖工程中岩体稳定分析有一定指导意义。
展开▼
