Hoek-Brown扰动系数D对边坡稳定性的影响

Hoek-Brown(HB)强度准则中的扰动系数D可反映爆破开挖对岩体扰动的程度。然而,在常规的数值模拟中,往往单一的D值被赋予到整个岩体工程中,这并不符合实际工程情况,因为岩体在未扰动区与爆破开挖扰动区的力学参数存在很大的差异。因此,本研究采用多平行坡面的分层建模方法来模拟D值随距爆破开挖面的距离增加而逐渐衰减的情况,分析了扰动系数D值变化对边坡稳定性的影响。首先,分析了爆破开挖扰动区厚度T对边坡安全系数FOS的影响。其次,分析了在爆破开挖扰动区内D值按3种变化规律 (上凸、线性、下凹) 衰减对边坡稳定性的影响。研究表明随着T的增加,边坡安全系数都呈下降的趋势,D值选用上凸曲线衰减得到的边坡安全系数相对其他2种衰减方式更加保守。该研究结果对HB准则在岩质边坡稳定性数值计算中的广泛应用有一定的参考价值。

Influence of Disturbance Factor D of Hoek-Brown Criterion on Slope Stability

The disturbance factor D of the Hoek-Brown (HB) criterion reflects the degree of rock damage caused by blasting and excavation. In general, the value of D is used for the whole rock mass which is different from the real blasting project where the rock mass is divided into undisturbed and blast damaged zones with different mechanical parameters. In this research, a new parallel layer model is adopted for simulating blast damaged zone to study the effect of disturbance factor D on the factor of safety (FOS) of rock mass slopes. Slope stability analysis is carried out not only to analyze the effect of blast damaged zone on FOS of a slope, but also to analyze the three types of changes of D values in the blast damaged zone (convex, linear, concave) for a given slope. Analysis results show that the values of FOS of a slope decrease with the increase of T (thickness of damaged zone) value, and FOS tends to be more conservative when D changes with convex curve.